- Tritium and deuterium labelling studies of alkali metal borohydrides and their application to simple reductions
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Simple and facile syntheses of highly deuterated and tritiated LiBH4, NaBH4 and KBH4 were achieved by hydrogen Isotope exchange with deuterium or tritium gas at elevated temperatures. The exchange products were characterized by boron, proton and deuterium or tritium NMR spectroscopy. The extent of isotope (2H or 3H) incorporation was calculated from the patterns of 11B NMR spectra. Several samples of tritiated NaBH4 were treated with BF3-Et2O to produce tritiated borane-THF complex, which is an electrophilic reducing agent. The utility of both the borohydride reagents and borane-THF complex in labelling reactions was confirmed by exemplary reductions leading to specifically labelled products. The extent and orientation of labelling in the reduction products was assessed by a combination of radio-HPLC analysis, 1H, 2H or 3H NMR and mass spectrometry.
- Than,Morimoto,Andres,Williams
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- Elucidation of a Sequential Iminium Ion Cascade Reaction Triggered by a Silica Gel-Promoted Aza-Peterson Reaction
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In a recent methodological study investigating the synthesis of N-alkoxyazomethine ylides, an unexpected aminal byproduct was generated during our attempt to isolate O-benzyl-N-((trimethylsilyl)methyl)hydroxylamine. After a strategic investigation, silica
- Jones, Elizabeth V.,Chen, Doris,Wright, Stephen W.,Trujillo, John I.,France, Stefan
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- Discovery of inhibitors and substrates of brassinin hydrolase: Probing selectivity with dithiocarbamate bioisosteres
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Brassinin hydrolase (BHAb), an inducible enzyme produced by the plant pathogen Alternaria brassicicola under stress conditions, catalyzes the hydrolysis of the methyl dithiocarbamate group of the phytoalexin brassinin, to indolyl-3-methanamine, methane thiol and carbonyl sulfide. Thirty four substrate inspired compounds, bioisosteres of brassinin and a range of related compounds, were evaluated as potential substrates and inhibitors of BHAb for the first time. While six compounds containing thiocarbamate, carbamate and carbonate groups displayed inhibitory activity against BHAb, only two were found to be substrates (thionecarbamate and dithiocarbamate). Methyl naphthalen-1-yl-methyl carbamate, the most potent inhibitor of the six, and methyl N′-(1-methyl- 3-indolylmethyl)carbamate inhibited BHAb through a reversible noncompetitive mechanism (Ki = 89 ± 9 and 695 ± 60 μM, respectively). Importantly, these carbamate inhibitors were resistant to degradation by A. brassicicola. Carbonates were also inhibitory of BHAb, but a quick degradation by A. brassicicola makes their potential use as crop protectants less likely. Overall, these results indicate that indolyl and naphthalenyl carbamates are excellent lead structures to design new paldoxins that could inhibit the detoxification of brassinin by A. brassicicola.
- Pedras, M. Soledade C.,Minic, Zoran,Hossain, Sajjad
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- Mechanistic Insights on Reduction of Carboxamides by Diisobutylaluminum Hydride and Sodium Hydride?Iodide Composite
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The reaction mechanisms on reduction of tertiary carboxamides by diisobutylaluminum hydride (DIBAL) and sodium hydride (NaH)-sodium iodide (NaI) composite were elucidated by the computational and experimental approaches. Reduction of N,N-dimethyl carboxamides with DIBAL provides the corresponding amines, whereas that with the NaH?NaI composite exclusively forms aldehyde even at high reaction temperature. DFT calculations revealed that dimeric structural nature of DIBAL and Lewis acidity on its Al center play crucial role to decompose the tetrahedral anionic carbinol amine intermediate through C?O bond cleavage. On the other hand, in the reduction with the NaH?NaI composite, the resulting tetrahedral anionic carbinol amine intermediate could be kept stable, thus providing aldehydes as a sole product by the aqueous workup.
- Ong, Derek Yiren,Watanabe, Kohei,Takita, Ryo,Chiba, Shunsuke
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- New [4]helicene derivatives: Synthesis, characterization and photophysical properties
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The design and synthesis of new [4]helicene derivatives were carried out by incorporating well-defined electron donor and acceptor groups at selected positions of the aromatic nuclei, aiming to use them in optical applications. Helicenes have been obtained in good overall yields through a five-step sequence involving mild experimental conditions and easy purification. Photophysical properties of these tetracyclic systems have been evaluated by UV–visible absorption and fluorescence spectroscopies and an emission in the visible region was observed.
- Hafedh, Nesrine,Aloui, Faouzi,Raouafi, Sondes,Dorcet, Vincent,Hassine, Béchir Ben
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- Design, synthesis, and antitumor activity of new bis-aminomethylnaphthalenes
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A new series of bis-aminomethylnaphthalenes were synthesized in satisfactory overall yield, through a simple synthetic strategy using reductive amination. The DNA binding properties of these compounds have been examined and compared to those of reference drugs using an UV spectroscopy method. The compounds were evaluated for their in vitro anticancer activity and some of them were studied in vivo. Compound 15 exhibited remarkable antitumor activity and represents a novel template for anticancer chemotherapy and can serve as a new lead compound.
- Bollini, Mariela,Casal, Juan Jose,Bruno, Ana Maria
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- Application of bis(phosphinite) pincer nickel complexes to the catalytic hydrosilylation of aldehydes
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A series of bis(phosphinite) (POCOP) pincer ligated nickel complexes, [2,6-(tBu2PO)2C6H3]NiX (X = SH, 1; SCH2Ph, 2; SPh, 3; NCS, 4; N3, 5), were used to catalyse the hydrosilylation of aldehydes. It was found that both complexes 1 and 2 are active in catalysing the hydrosilylation of aldehydes with phenylsilane and complex 1 is comparatively more active. The expected alcohols were isolated in good to excellent yields after basic hydrolysis of the resultant hydrosilylation products. However, no reaction was observed when complex 3 or 4 or 5 was used as the catalyst. The results are consistent with complexes 1 and 2 serving as catalyst precursors, which generate the corresponding nickel hydride complex [2,6-(tBu2PO)2C6H3]NiH in situ, and the nickel hydride complex is the active species that catalyses this hydrosilylation process. The in situ generation of the nickel hydride species was supported by both experimental results and DFT calculation.
- Chang, Jiarui,Fang, Fei,Tu, Chenhao,Zhang, Jie,Ma, Nana,Chen, Xuenian
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- Amino-polystyrene supported hexaethylene glycol-bridged ionic liquid as an efficient heterogeneous catalyst for water-mediated nucleophilic hydroxylation
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We report a simple and eco-friendly method for producing an amino-polystyrene supported hexaethylene glycol-bridged ionic liquid (APS-HEGBIL) based on the copolymerization of amino-styrene with 1-vinyl imidazolium ionic liquid bearing hexaethylene glycol moieties, and its characterization by several analytical techniques. The resulting APS-HEGBIL catalyst was found to be remarkably efficient at catalyzing the selective nucleophilic hydroxylation of alkyl halides to produce the corresponding alcohols in water, which acted as a solvent and a nucleophilic hydroxide source. The catalyst was easily recycled and maintained its catalytic activity and stability after ten cycles with excellent yields. The main attributes of the catalyst were that it significantly enhanced the nucleophilicity of water during reactions and promoted the rapid conversions of polar and base-sensitive alkyl halide reactants to alcohols in excellent yields. The combination of ionic liquids and polymeric materials afforded quasi-homogeneous catalysts that were recycled by simple filtration and provided environmentally benign means for conducted catalytic procedures.
- Reddy, Mudumala Veeranarayana,Kang, Seok Min,Yoo, Suah,Woo, Sang Sik,Kim, Dong Wook
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- One-Shot Double Amination of Sondheimer-Wong Diynes: Synthesis of Photoluminescent Dinaphthopentalenes
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Photoluminescent diamino-substituted dinaphthopentalenes were synthesized successfully by the treatment of in situ prepared dinaphthocyclooctadiyne with lithium amide. This reaction involves a series of transformations including the nucleophilic addition
- Xu, Feng,Peng, Lifen,Shinohara, Kenta,Nishida, Takanori,Wakamatsu, Kan,Uejima, Motoyuki,Sato, Tohru,Tanaka, Kazuyoshi,Machida, Norihiko,Akashi, Haruo,Orita, Akihiro,Otera, Junzo
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- The Asymmetric Ullmann Coupling Reaction of (S)-2,2'-Bis(1-bromo-2-naphthoyloxy)-1,1'-binaphtyl Revisited. Formation of 24-Membered Optically Pure Cyclic Dimer as Well as 12-Membered Cyclic Monomer
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The copper-promoted Ullmann reaction of the title diester proceeded with high stereoselectivity to give 24-membered optically pure cyclic dimer of (S,S,S,S)-configuration as well as 12-membered monomeric cycle of (S,S)-configuration.The reaction also gave reduced, open-chain dimer enriched in (S,R,S)-diastereomer(S,S,S)-counterpart (17percent d.e.).Stereochemical course to the cyclic dimer was discussed considering the result that the intermolecular Ullmann coupling of chiral alcohol esters of 1-bromo-2-naphthoic acid poorly induced axial chirality in the joining of the two naphthyl units.
- Miyano, Sotaro,Handa, Shigeru,Tobita, Masayuki,Hashimoto, Harukichi
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- Cytochrome P450BM-3 reduces aldehydes to alcohols through a direct hydride transfer
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Cytochrome P450BM-3 catalyzed the reduction of lipophilic aldehydes to alcohols efficiently. A kcat of ~25min-1 was obtained for the reduction of methoxy benzaldehyde with wild type P450BM-3 protein which was higher than in the isolated reductase domain (BMR) alone and increased in specific P450-domain variants. The reduction was caused by a direct hydride transfer from preferentially R-NADP2H to the carbonyl moiety of the substrate. Weak substrate-P450-binding of the aldehyde, turnover with the reductase domain alone, a deuterium incorporation in the product from NADP2H but not D2O, and no inhibition by imidazole suggests the reductase domain of P450BM-3 as the potential catalytic site. However, increased aldehyde reduction by P450 domain variants (P450BM-3 F87A T268A) may involve allosteric or redox mechanistic interactions between heme and reductase domains. This is a novel reduction of aldehydes by P450BM-3 involving a direct hydride transfer and could have implications for the metabolism of endogenous substrates or xenobiotics.
- Kaspera, Rüdiger,Sahele, Tariku,Lakatos, Kyle,Totah, Rheem A.
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- PH clock instructed transient supramolecular peptide amphiphile and its vesicular assembly
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A new strategy to construct a transient supramolecular peptide amphiphile (SPA) and its vesicular aggregates is displayed. The construction of the amphiphile is assisted by the ternary complexation of cucurbit[8]uril and pH responsive imine bond formation. The transient assembly follows a pH clock set by urea/urease and hydrolysis of glucono delta-lactone (GdL). The transient assembly can be repeated for several cycles through feeding the system with the fuel (urea).
- Dowari, Payel,Das, Saurav,Pramanik, Bapan,Das, Debapratim
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- The tert-butyl chloride-lithium naphthalene radical anion and tert-butyllithium-naphthalene systems. Mechanism of metallation
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A mechanism of lithiation of aromatics has been inferred from a comparative study of the systems tert-butyl chloride-lithium naphthalene radical anion and tert-butyllithium-naphthalene. Both systems give tert-butyldihydronaphthyllithiums, naphthyllithiums and tert-butylnaphthalenes. Although tert-butyllithium is a reaction product in the former system, it has been shown not to be involved in the formation of the products. In the system tert-butyllithium-naphthalene the distribution of products is markedly dependent upon the strength of the catalyzing Lewis base. Weak Lewis bases favor formation of tert-butylnaphthalene (mainly the 2-isomer) as well as tert-butyldihydronaphthyllithiums, whereas strong Lewis bases favor metallation. Mechanisms are proposed which postulate the involvement of a tert-butyl radical-naphthalene donor-acceptor complex in the fundamental elementary reaction.
- Screttas, Constantinos G.,Micha-Screttas, Maria,Steele, Barry R.
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- Platinum thiolate complexes supported by PBP and POCOP pincer ligands as efficient catalysts for the hydrosilylation of carbonyl compounds
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Diphosphino-boryl-based PBP pincer platinum thiolate complexes, [Pt(SR){B(NCH2PtBu2)2-1,2-C6H4}] (R = H, 1a; Ph, 1b), and benzene-based bisphosphinite POCOP pincer platinum thiolate complexes, [Pt(SR)(tBu2PO)2-1,3-C6H3] (R = H, 2a; Ph, 2b), were prepared
- Chang, Jiarui,Chen, Xuenian,Xue, Man-Man,Zhang, Jie
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supporting information
p. 2304 - 2312
(2022/02/21)
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- Nickel-Catalyzed Reductive Cross-Coupling of Benzylic Sulfonium Salts with Aryl Iodides
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A nickel-catalyzed cross-electrophile coupling of benzylic sulfonium salts with aryl iodides has been developed, providing direct access to diarylalkanes from readily available and stable coupling partners. Preliminary mechanistic studies suggest that the C-S bond cleavage proceeds through a single-electron transfer process to generate a benzylic radical.
- Wang, Wei,Yao, Ken,Wu, Fan
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supporting information
p. 361 - 366
(2022/03/07)
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- Hydrogenation of Esters by Manganese Catalysts
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The hydrogenation of esters catalyzed by a manganese complex of phosphine-aminopyridine ligand was developed. Using this protocol, a variety of (hetero)aromatic and aliphatic carboxylates including biomass-derived esters and lactones were hydrogenated to primary alcohols with 63–98% yields. The manganese catalyst was found to be active for the hydrogenation of methyl benzoate, providing benzyl alcohol with turnover numbers (TON) as high as 45,000. Investigation of catalyst intermediates indicated that the amido manganese complex was the active catalyst species for the reaction. (Figure presented.).
- Li, Xiao-Gen,Li, Fu,Xu, Yue,Xiao, Li-Jun,Xie, Jian-Hua,Zhou, Qi-Lin
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p. 744 - 749
(2022/01/13)
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- Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
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Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
- Yi, Jaeeun,Kim, Hyun Tae,Jaladi, Ashok Kumar,An, Duk Keun
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p. 129 - 132
(2021/11/17)
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- Chemoselective Deoxygenation of 2° Benzylic Alcohols through a Sequence of Formylation and B(C6F5)3-Catalyzed Reduction
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A sequence of formylation and B(C6F5)3-catalyzed reduction of the resulting formate with Et3SiH enables the chemoselective deoxygenation of secondary benzylic alcohols. Primary benzylic and tertiary non-benzylic alcohols are not reduced by this protocol. The formyl group fulfills a double role as activator and self-sacrificing protecting group. The deoxygenation of these formates is fast and can be carried out in the presence of other potentially reducible groups. Neighboring-group participation was found in the deoxygenation of certain diol motifs.
- Oestreich, Martin,Richter, Sven C.
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supporting information
p. 2103 - 2106
(2021/07/22)
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- A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
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Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
- Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
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supporting information
p. 16865 - 16873
(2021/10/20)
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- Ambient-pressure highly active hydrogenation of ketones and aldehydes catalyzed by a metal-ligand bifunctional iridium catalyst under base-free conditions in water
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A green, efficient, and high active catalytic system for the hydrogenation of ketones and aldehydes to produce corresponding alcohols under atmospheric-pressure H2 gas and ambient temperature conditions was developed by a water-soluble metal–ligand bifunctional catalyst [Cp*Ir(2,2′-bpyO)(OH)][Na] in water without addition of a base. The catalyst exhibited high activity for the hydrogenation of ketones and aldehydes. Furthermore, it was worth noting that many readily reducible or labile functional groups in the same molecule, such as cyan, nitro, and ester groups, remained unchanged. Interestingly, the unsaturated aldehydes can be also selectively hydrogenated to give corresponding unsaturated alcohols with remaining C=C bond in good yields. In addition, this reaction could be extended to gram levels and has a large potential of wide application in future industrial.
- Wang, Rongzhou,Yue, Yuancheng,Qi, Jipeng,Liu, Shiyuan,Song, Ao,Zhuo, Shuping,Xing, Ling-Bao
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- Synthesis, Structure, and Catalytic Hydrogenation Activity of [NO]-Chelate Half-Sandwich Iridium Complexes with Schiff Base Ligands
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A series of N,O-coordinate iridium(III) complexes with a half-sandwich motif bearing Schiff base ligands for catalytic hydrogenation of nitro and carbonyl substrates have been synthesized. All iridium complexes showed efficient catalytic activity for the hydrogenation of ketones, aldehydes, and nitro-containing compounds using clean H2 as reducing reagent. The iridium catalyst displayed the highest TON values of 960 and 950 in the hydrogenation of carbonyl and nitro substrates, respectively. Various types of substrates with different substituted groups afforded corresponding products in excellent yields. All N,O-coordinate iridium(III) complexes 1-4 were well characterized by IR, NMR, HRMS, and elemental analysis. The molecular structure of complex 1 was further characterized by single-crystal X-ray determination.
- Lv, Wen-Rui,Li, Rong-Jian,Liu, Zhen-Jiang,Jin, Yan,Yao, Zi-Jian
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p. 8181 - 8188
(2021/05/26)
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- Oxoammonium-Mediated Allylsilane–Ether Coupling Reaction
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A new C(sp3)?H functionalization reaction consisting of the oxidative α-allylation of allyl- and benzyl- methyl ethers has been developed. The C?C coupling could be carried out under mild conditions thanks to the use of cheap and green oxoammonium salts. The scope of the reaction was studied over 27 examples, considering the nature of the substituents on the two coupling partners.
- Carlet, Federica,Bertarini, Greta,Broggini, Gianluigi,Pradal, Alexandre,Poli, Giovanni
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supporting information
p. 2162 - 2168
(2021/04/02)
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- Light-driven MPV-type reduction of aryl ketones/aldehydes to alcohols with isopropanol under mild conditions
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Alcohols are versatile structural motifs of pharmaceuticals, agrochemicals and fine chemicals. With respect to green chemistry, the development of more sustainable and cost-efficient processes for converting ketones/aldehydes to alcohols is highly desired. Herein, a direct light-driven strategy for reducing ketones/aldehydes to alcohols using isopropanol as the reducing agent and solvent, in the presence of t-BuOLi, under an air atmosphere at room temperature is developed. This operationally simple light-promoted Meerwein-Ponndorf-Verley (MPV) type reduction can be used to produce various benzylic alcohol derivatives as well as applied to bioactive molecules and PEEK model compounds, demonstrating its application potential.
- Cao, Dawei,Xia, Shumei,Pan, Pan,Zeng, Huiying,Li, Chao-Jun,Peng, Yong
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supporting information
p. 7539 - 7543
(2021/10/12)
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- Interrupting the Barton?McCombie reaction: Aqueous deoxygenative trifluoromethylation of o-alkyl thiocarbonates
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The site-selective trifluoromethylation of aliphatic systems remains an important challenge. This work describes a light-driven, copper-mediated trifluoromethylation of O-alkyl thiocarbonates. The reaction provides broad functional group tolerance (e.g., alkyne, alkene, phenol, free alcohol, electron-rich and -deficient arenes), thereby offering orthogonality and practicality for trifluoromethylation. A radical organometallic mechanism is proposed.
- Liu, Zhi-Yun,Cook, Silas P.
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supporting information
p. 808 - 813
(2021/02/01)
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- Efficient Solvent-Free Hydrosilylation of Aldehydes and Ketones Catalyzed by Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH
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An efficient solvent-free catalyst system for hydrosilylation of aldehydes and ketones was developed based on iron pre-catalyst Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH. The reactions were tolerant of many functional groups and the corresponding alcohols were isolated in good to excellent yields following basic hydrolysis of the reaction products. The reaction is likely catalyzed by an in situ generated pincer ligated iron hydride complex. Graphic Abstract: [Figure not available: see fulltext.]
- Fang, Fei,Chang, Jiarui,Zhang, Jie,Chen, Xuenian
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p. 3509 - 3515
(2021/03/16)
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- Sodium Aminodiboranate, a New Reagent for Chemoselective Reduction of Aldehydes and Ketones to Alcohols
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Sodium aminodiboranate (NaNH 2(BH 3) 2, NaADBH) is a new member of the old borane family, which exhibits superior performance in chemoselective reduction. Experimental results show that NaADBH can rapidly reduce aldehydes and ketones to the corresponding alcohols in high efficiency and selectivity under mild conditions. There are little steric and electronic effects on this reduction.
- Wang, Jin,Guo, Yu,Li, Shouhu,Chen, Xuenian
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p. 1104 - 1108
(2021/05/25)
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- A method of synthesis of alcohols
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The present invention belongs to the field of organic synthesis technology, specifically a synthesis method of an alcohol; the present invention is under the catalytic action of tert-butanol lithium, with ester compounds and pinacol borane as raw materials, tetrahydrofuran as a solvent, reacted at 100 ° C for 24h, followed by adding 2mol / LNaOH / MeOH solution, stirred at room temperature overnight to obtain alcohol compounds; the raw materials of the present invention are of extensive sources or easy to prepare, the reaction conditions are relatively mild and do not require a large number of / cumbersome additives, in addition to the tert-butanol lithium catalyst is simple, And the prepared alcohol compounds are of high quality and high separation yield.
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Paragraph 0049-0054
(2022/01/10)
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- CeO2-nanocubes as efficient and selective catalysts for the hydroboration of carbonyl groups
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The CeO2-nanoparticle catalysed hydroboration of carbonyl compounds with HBpin (pin = OCMe2CMe2O) is reported to afford the corresponding borate esters in excellent yield. A series of aromatic and aliphatic aldehydes and ketones having synthetically important functional groups were well-Tolerated under mild reaction conditions. Further, chemoselective hydroboration of aldehydes over other reducible functional groups such as ketone, nitrile, hydroxide, alkene, alkyne, amide, ester, nitro, and halides was achieved. Importantly the catalyst can be recycled up to ten runs with slight loss in activity. This journal is
- Bhawar, Ramesh,Bose, Shubhankar Kumar,Patil, Kiran S.
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supporting information
p. 15028 - 15034
(2021/09/04)
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- Selective catalytic synthesis of bio-based terephthalic acid from lignocellulose biomass
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_Efficient synthesis of bio-based chemicals from renewable lignocellulosic biomass is of great significance to promote the sustainable development of chemical industry. This work aims to demonstrate that terephthalic acid, a bulk high value chemical in petrochemical industry, can be synthesized using biomass. This novel controllable transformation process was started with the selective catalytic pyrolysis of sawdust biomass to form p-xylene intermediate. The high p-xylene yield of 23.4% was obtained using the Ga2O3/SiO2/HZSM-5 catalyst under the optimized reaction condition. Subsequently, the selective oxidation of the biomass-derived aromatic intermediates to terephthalic acid was realized with the metal oxide catalysts. The highest terephthalic acid yield of 72.8% with the terephthalic acid selectivity of 82.3% was achieved using the CoMn2O4@SiO2@Fe3O4 catalyst. Based on the study of the catalytic conversion of the model compounds and the catalyst characterizations, the reaction pathways and possible reaction mechanism have been proposed.
- Fan, Minghui,He, Yuting,Li, Quanxin,Luo, Yuehui,Yang, Mingyu,Zhang, Yanhua,Zhu, Lijuan
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- Biocatalytic reduction of α,β-unsaturated carboxylic acids to allylic alcohols
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We have developed robust in vivo and in vitro biocatalytic systems that enable reduction of α,β-unsaturated carboxylic acids to allylic alcohols and their saturated analogues. These compounds are prevalent scaffolds in many industrial chemicals and pharmaceuticals. A substrate profiling study of a carboxylic acid reductase (CAR) investigating unexplored substrate space, such as benzo-fused (hetero)aromatic carboxylic acids and α,β-unsaturated carboxylic acids, revealed broad substrate tolerance and provided information on the reactivity patterns of these substrates. E. coli cells expressing a heterologous CAR were employed as a multi-step hydrogenation catalyst to convert a variety of α,β-unsaturated carboxylic acids to the corresponding saturated primary alcohols, affording up to >99percent conversion. This was supported by the broad substrate scope of E. coli endogenous alcohol dehydrogenase (ADH), as well as the unexpected CC bond reducing activity of E. coli cells. In addition, a broad range of benzofused (hetero)aromatic carboxylic acids were converted to the corresponding primary alcohols by the recombinant E. coli cells. An alternative one-pot in vitro two-enzyme system, consisting of CAR and glucose dehydrogenase (GDH), demonstrates promiscuous carbonyl reductase activity of GDH towards a wide range of unsaturated aldehydes. Hence, coupling CAR with a GDH-driven NADP(H) recycling system provides access to a variety of (hetero)aromatic primary alcohols and allylic alcohols from the parent carboxylates, in up to >99percent conversion. To demonstrate the applicability of these systems in preparative synthesis, we performed 100 mg scale biotransformations for the preparation of indole-3-aldehyde and 3-(naphthalen-1-yl)propan-1-ol using the whole-cell system, and cinnamyl alcohol using the in vitro system, affording up to 85percent isolated yield.
- Aleku, Godwin A.,Leys, David,Roberts, George W.
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p. 3927 - 3939
(2020/07/09)
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- Diethylsilane as a Powerful Reagent in Au Nanoparticle-Catalyzed Reductive Transformations
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Diethylsilane (Et2SiH2), a simple and readily available dihydrosilane, that exhibits superior reactivity, as compared to monohydrosilanes, in a series of reductive transformations catalyzed by recyclable and reusable Au nanoparticles (1 mol-%) supported on TiO2. It reduces aldehydes or ketones almost instantaneously at ambient conditions. It can be used in a one pot rapid reductive amination procedure, in which premixing of aldehyde and amine is required prior to the addition of the reducing agent and the catalyst, even in a protic solvent. An unprecedented method for the synthesis of N-arylisoindolines is also shown in the reductive amination between o-phthalaldehyde and anilines. In this transformation, it is proposed that the intermediate N,2-diphenylisoindolin-1-imines are reduced stepwise to the isoindolines. Finally, Et2SiH2 readily reduces amides into amines in excellent yields and shorter reaction times relative to previously known analogous nano Au(0)-catalyzed protocols.
- Louka, Anastasia,Kidonakis, Marios,Saridakis, Iakovos,Zantioti-Chatzouda, Elisavet-Maria,Stratakis, Manolis
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p. 3508 - 3514
(2020/06/02)
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- Oxidized graphitic carbon nitride as a sustainable metal-free catalyst for hydrogen transfer reactions under mild conditions
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The development of green and sustainable transfer hydrogenation protocols without the use of expensive noble metals and toxic solvents is a challenging task. Herein, a highly stable, low-cost, metal-free heterogeneous catalyst, oxidized graphitic carbon nitride (O-GCN), has been developed, which exhibits efficient catalytic hydrogen transfer reactions of carbonyl compounds to corresponding alcohols under mild reaction conditions. The heterogeneous catalyst was synthesized by the chemical oxidation of graphitic carbon nitride (GCN) nanosheets, which results in the generation of carboxyl, hydroxyl and ketone groups over the GCN surface. These hydrophilic groups functionalized on the surface of O-GCN nanosheets act as catalytically active sites for the hydrogen transfer reactions of carbonyl compounds. A wide range of substrates was investigated for the hydrogen transfer reactions using 2-propanol both as a hydrogen donor and a solvent. The O-GCN nanosheets resulted in high yields and high turnover numbers (TON) demonstrating the versatile catalytic potential of the as-synthesized catalyst. The detailed optimization of the reaction parameters (temperature, time and catalyst amount) was performed, in addition to the calculation of green metric parameters. Moreover, the catalyst could be easily recovered and was used for five runs without any significant loss in catalytic activity. This study provides a green, sustainable, attractive, and useful methodology for the hydrogen transfer reactions of a wide range of carbonyl compounds.
- Bahuguna, Ashish,Choudhary, Priyanka,Dhankhar, Sandeep Singh,Krishnan, Venkata,Kumar, Ajay,Nagaraja, C. M.
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p. 5084 - 5095
(2020/08/25)
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- Diboron-Mediated Rhodium-Catalysed Transfer Hydrogenation of Alkenes and Carbonyls
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A diboron-mediated rhodium-catalysed transfer hydrogenation system using water as the hydrogen donor is developed. In addition to a series of alkenes with good functional group tolerance, this rhodium-based catalytic system also effectively reduces aldehydes and ketones. A plausible mechanism involving the RhI-catalysed hydrogen generation and Rh0-catalysed hydrogenation is proposed for the reaction.
- Lin, Xiao,Wang, Yuhan,Hu, Yan,Zhu, Wanjiang,Dou, Xiaowei
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supporting information
p. 1046 - 1049
(2020/02/25)
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- A facile and highly efficient transfer hydrogenation of ketones and aldehydes catalyzed by palladium nanoparticles supported on mesoporous graphitic carbon nitride
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A novel transfer hydrogenation methodology for the reduction of ketones (14 examples) and benzaldehyde derivatives (12 examples) to the corresponding alcohols using Pd nanoparticles supported on mesoporous graphitic carbon nitride (mpg-C3N4/Pd) as a reusable catalyst and ammonia borane as a safe hydrogen source in an aqueous solution MeOH/H2O (v/v = 1/1) is described. The catalytic hydrogenation reactions were conducted in a commercially available high-pressure glass tube at room temperature, and the corresponding alcohols were obtained in high yields in 2–5 min. Moreover, the presented transfer hydrogenation protocol shows partial halogen selectivity with bromo-, fluoro-, and chloro-substituted carbonyl analogs. In addition, the present catalyst can be reused up to five times without losing its efficiency, and scaling-up the reaction enables α-methylbenzyl alcohol to be produced in 90% isolated yield.
- Ni?anc?, Bilal,Da?alan, Ziya
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- Hydrosilylation of Aldehydes and Ketones Catalysed by Bis(phosphinite) Pincer Platinum Hydride Complexes
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Bis(phosphinite) pincer platinum hydride complexes, [2,6-(R2PO)2C6H3]PtH (R=tBu, iPr), were synthesized, characterized and applied to the hydrosilylation of aldehydes and ketones. NMR study and single crystal X-ray diffraction analysis indicated that the hydrides in these two platinum complexes are comparatively less hydridic: down-field 1H NMR resonances (0.71 and 0.98 ppm) and weak Pt?H interactions were observed. Both the platinum complexes were found to be good catalysts for the hydrosilylation of aldehydes and ketones with phenylsilane. The corresponding alcohols were isolated in good to excellent yields following basic hydrolysis of the resultant hydrosilylation products and turnover frequencies (TOFs) up to 3200 h?1 were achieved at 60 °C in toluene, which are much higher than those of the hydrosilylation catalysed by the corresponding nickel pincer hydride complexes. A possible mechanism for the present hydrosilylation process was discussed. (Figure presented.).
- Chang, Jiarui,Fang, Fei,Zhang, Jie,Chen, Xuenian
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p. 2709 - 2715
(2020/06/02)
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- Nickel-Catalyzed Amination of α-Aryl Methyl Ethers
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α-Aryl amines are prevalent in pharmaceutically active compounds and natural products. Herein, we describe a Ni-catalyzed protocol for their synthesis from readily available α-aryl ethers. While α-aryl ethers have been used as electrophiles in Ni-catalyzed C-C bond formations, their use in C-heteroatom bond formation is much less prevalent. Preliminary mechanistic insight suggests that oxidative addition is facilitated by an anionic ligand and that reductive elimination is a reversible process.
- Patel, Purvish,Rousseaux, Sophie A. L.
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supporting information
p. 492 - 496
(2020/03/13)
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- Lithium Bromide/HBpin: A Mild and Effective Catalytic System for the Selective Hydroboration of Aldehydes and Ketones
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The catalytic hydroboration of aldehydes and ketones with HBpin was examined using simple and commercially available metal salts (Li, Na, and K). Among the tested salts, LiBr (0.5–1.0 mol%) was found to be an efficient catalyst for the hydroboration of various aldehydes and ketones at room temperature. Further, the chemoselective hydroboration of aldehydes over ketones was also demonstrated.
- An, Duk Keun,Choi, Hyeon Seong,Hwang, Hyonseok,Kim, Hanbi,Lee, Ji Hye,Shin, Hye Lim,Yi, Jaeeun
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p. 1009 - 1018
(2020/10/12)
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- Combined KOH/BEt3Catalyst for Selective Deaminative Hydroboration of Aromatic Carboxamides for Construction of Luminophores
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The selective catalytic C-N bond cleavage of amides into value-added amine products is a desirable but challenging transformation. Molecules containing iminodibenzyl motifs are prevalent in pharmaceutical molecules and functional materials. Here we established a combined KOH/BEt3 catalyst for deaminative hydroboration of acyl-iminodibenzyl derivatives, including nonheterocyclic carboxamides, to the corresponding amines. This novel transition-metal-free methodology was also applied to the construction of Clomipramine and luminophores.
- Li, Jinshan,Wang, Jiali,Yang, Jianguo,Yao, Wubing,Zhong, Aiguo
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p. 8086 - 8090
(2020/11/03)
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- Direct benzylation of amines with benzylic alcohols catalyzed by palladium/phosphine-borane catalyst system
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Direct catalytic benzylation of amines with benzylic alcohols to give benzylamines has been newly developed by using palladium/phosphine-borane catalyst system. In this catalytic reaction, the linking between both phosphine and borane moieties in the ligand is very important. Hydroxy group of benzylic alcohols is activated by Lewis acidic borane to form a benzylpalladium intermediate which is attacked by amines to give benzylamine products.
- Onodera, Gen,Kumagae, Hidenobu,Nakamura, Daiki,Hayasaki, Takuto,Fukuda, Tsutomu,Kimura, Masanari
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supporting information
(2020/11/04)
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- Group 6 Metal Carbonyl Complexes Supported by a Bidentate PN Ligand: Syntheses, Characterization, and Catalytic Hydrogenation Activity
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We report on the preparation of a series of phosphorus-nitrogen donor ligand complexes [M(CO)4(PN)], where M = Cr, Mo, W and PN is 2-(diphenylphosphino)ethylamine. The organometallic compounds were readily obtained upon reacting the respective metal hexacarbonyls with equimolar amounts of the pertinent ligand in the presence of tetraethylammonium bromide. The PN-ligated metal carbonyls were fully characterized by standard spectroscopic techniques and X-ray crystallography. The ability of the title compounds to function as homogeneous hydrogenation catalysts was probed in the reduction of acetophenone and benzaldehyde derivatives to yield the corresponding alcohols. The reaction setup was easily assembled by simply combining the components in the autoclave on the bench outside an inert-gas-operated glovebox system.
- Faust, Kirill,Topf, Christoph,Vielhaber, Thomas
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p. 4535 - 4543
(2020/12/23)
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- Continuous-Flow Amide and Ester Reductions Using Neat Borane Dimethylsulfide Complex
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Reductions of amides and esters are of critical importance in synthetic chemistry, and there are numerous protocols for executing these transformations employing traditional batch conditions. Notably, strategies based on flow chemistry, especially for amide reductions, are much less explored. Herein, a simple process was developed in which neat borane dimethylsulfide complex (BH3?DMS) was used to reduce various esters and amides under continuous-flow conditions. Taking advantage of the solvent-free nature of the commercially available borane reagent, high substrate concentrations were realized, allowing outstanding productivity and a significant reduction in E-factors. In addition, with carefully optimized short residence times, the corresponding alcohols and amines were obtained in high selectivity and high yields. The synthetic utility of the inexpensive and easily implemented flow protocol was further corroborated by multigram-scale syntheses of pharmaceutically relevant products. Owing to its beneficial features, including low solvent and reducing agent consumption, high selectivity, simplicity, and inherent scalability, the present process demonstrates fewer environmental concerns than most typical batch reductions using metal hydrides as reducing agents.
- ?tv?s, Sándor B.,Kappe, C. Oliver
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p. 1800 - 1807
(2020/02/27)
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- Exhaustive Reduction of Esters Enabled by Nickel Catalysis
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We report a one-step procedure to directly reduce unactivated aryl esters into their corresponding tolyl derivatives. This is achieved by an organosilane-mediated ester hydrosilylation reaction and subsequent Ni/NHC-catalyzed hydrogenolysis. The resulting conditions provide a direct and efficient alternative to multi-step procedures for this transformation that often require the use of hazardous metal hydrides. Applications in the synthesis of -CD3-containing products, derivatization of bioactive molecules, and chemoselective reduction in the presence of other C-O bonds are demonstrated.
- Cook, Adam,Prakash, Sekar,Zheng, Yan-Long,Newman, Stephen G.
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supporting information
p. 8109 - 8115
(2020/05/20)
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- Ruthenium-catalyzed ester reductions applied to pharmaceutical intermediates
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Ruthenium pincer complexes were synthesized and used for catalytic ester reductions under mild conditions (~5 bar of hydrogen). An experimental design approach was used to optimize the conditions for yield, purity, and robustness. Evidence for the catalytically active ruthenium dihydride species is presented. Observed intermediates and side products, as well as time-course data, were used to build mechanistic insight. The optimized procedure was further demonstrated through scaled-up reductions of two pharmaceutically relevant esters, both in batch and continuous flow.
- Shaalan, Youssef,Boulton, Lee,Jamieson, Craig
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supporting information
p. 2745 - 2751
(2020/11/30)
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- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- Metal-Free Synthesis of Phenol-Aryl Selenides via Dehydrogenative C-Se Coupling of Aryl Selenoxides with Phenols
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Herein, we disclose the synthesis of diaryl selenides through an unexpected C-Se coupling between aryl benzyl selenoxides and phenols. The synthetic significance of the method is that it provides a mild, rapid, and metal-free access to organoselenides in high yields with excellent functional group tolerance. This coupling of aryl benzyl selenoxides reveals a completely new reaction possibility compared with aryl sulfoxides. We also probed the reaction mechanism of this unexpected transformation through experimental studies and revealed a special Se(IV)-Se(III)-Se(II) reaction pathway.
- Liu, Zhengfen,Jiang, Yonggang,Liu, Chunxiang,Zhang, Linlin,Wang, Jing,Li, Tiantian,Zhang, Hongbin,Li, Minyan,Yang, Xiaodong
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p. 7386 - 7398
(2020/08/21)
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- Exploration of the Fluoride Reactivity of Aryltrifluoroborate on Selective Cleavage of Diphenylmethylsilyl Groups
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The first known report on the fluoride catalytic reactivity of potassium aryltrifluoroborate is described. The fluoride reactivity of phenyltrifluoroborate was controlled by substituents on the trifluoroborate-attached benzene, such as the methoxy group a
- Fujiki, Katsumasa,Tanaka, Katsunori
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supporting information
p. 4616 - 4620
(2020/07/06)
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- Synthesis and Reactivity of Fluorinated Triaryl Aluminum Complexes
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The addition of the Grignard 3,4,5-ArFMgBr to aluminum(III) chloride in ether generates the novel triarylalane Al(3,4,5-ArF)3·OEt2. Attempts to synthesize this alane via transmetalation from the parent borane with trimethylaluminum gave a dimeric structure with bridging methyl groups, a product of partial transmetalation. On the other hand, the novel alane Al(2,3,4-ArF)3 was synthesized from the parent borane and trimethylaluminum. Interestingly, the solid-state structure of Al(2,3,4-ArF)3 shows an extended chain structure resulting from neighboring Al···F contacts. Al(3,4,5-ArF)3·OEt2 was then found to be an effective catalyst for the hydroboration of carbonyls, imines, and alkynes with pinacolborane.
- Ould, Darren M. C.,Carden, Jamie L.,Page, Rowan,Melen, Rebecca L.
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supporting information
p. 14891 - 14898
(2020/10/02)
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- Bulky N-Heterocyclic-Carbene-Coordinated Palladium Catalysts for 1,2-Addition of Arylboron Compounds to Carbonyl Compounds
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The synthesis of primary, secondary, and tertiary alcohols by the 1,2-addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible N-heterocyclic carbene (NHC)-coordinated 2,6-di(pentan-3-yl)aniline (IPent)-based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS-IPent-CYP-catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2-addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
- Okuda, Yuta,Nagaoka, Masahiro,Yamamoto, Tetsuya
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p. 6291 - 6300
(2020/11/30)
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- A General Method for Photocatalytic Decarboxylative Hydroxylation of Carboxylic Acids
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A general and practical method for decarboxylative hydroxylation of carboxylic acids was developed through visible light-induced photocatalysis using molecular oxygen as the green oxidant. The addition of NaBH4 to in situ reduce the unstable peroxyl radical intermediate much broadened the substrate scope. Different sp3 carbon-bearing carboxylic acids were successfully employed as substrates, including phenylacetic acid-type substrates, as well as aliphatic carboxylic acids. This transformation worked smoothly on primary, secondary, and tertiary carboxylic acids.
- Khan, Shah Nawaz,Zaman, Muhammad Kashif,Li, Ruining,Sun, Zhankui
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p. 5019 - 5026
(2020/05/01)
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- Lithium tert-Butoxide-catalyzed Hydroboration of Carbonyl Compounds
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We report the successful hydroboration of aldehydes and ketones with pinacolborane using 1 mol % lithium tert-butoxide under ambient conditions. The present protocol was applicable to various aldehydes and ketones, and the corresponding boronate esters and subsequent alcohols were obtained in good to excellent yields. In addition, this high-yielding practical method could be extended to the reduction of ester groups. Under optimized conditions, LiOtBu facilitate the hydroboration of ester groups quantitatively.
- Kim, Jea Ho,Jaladi, Ashok Kumar,Kim, Hyun Tae,An, Duk Keun
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p. 971 - 975
(2019/08/30)
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- Polymer-Anchored Bifunctional Pincer Catalysts for Chemoselective Transfer Hydrogenation and Related Reactions
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A series of polymer-supported cooperative PC(sp3)P pincer catalysts was synthesized and characterized. Their catalytic activity in the acceptorless dehydrogenative coupling of alcohols and the transfer hydrogenation of aldehydes with formic acid as a hydrogen source was investigated. This comparative study, examining homogeneous and polymer-tethered species, proved that carefully designing a link between the support and the catalytic moiety, which takes into consideration the mechanism underlying the target transformation, might lead to superior heterogeneous catalysis.
- Mujahed, Shrouq,Valentini, Federica,Cohen, Shirel,Vaccaro, Luigi,Gelman, Dmitri
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p. 4693 - 4699
(2019/10/28)
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- Borinic Acid Mediated Hydrosilylations: Reductions of Carbonyl Derivatives
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4-Fluoro-2-chlorophenylborinic acid acts as a precatalyst in the presence of phenylsilane for the facile reduction of ketones, aldehydes and imines. Notably, synergistic mediation of a tertiary amine was found essential to trigger silicon to boron hydride transfer to generate a key amine–diarylhydroborane Lewis complex.
- Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 995 - 998
(2018/12/13)
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- Polypyridyl iridium(III) based catalysts for highly chemoselective hydrogenation of aldehydes
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Iridium-catalyzed transfer hydrogenation (TH) of carbonyl compounds using HCOOR (R = H, Na, NH4) as a hydrogen source is a pivotal process as it provides the clean process and is easy to execute. However, the existing highly efficient iridium catalysts work at a narrow pH; thus, does not apply to a wide variety of substrates. Therefore, the development of a new catalyst which works at a broad pH range is essential as it can gain a broader scope of utilization. Here we report highly efficient polypyridyl iridium(III) catalysts, [Ir(tpy)(L)Cl](PF6)2 {where tpy = 2,2′:6′,2′'-Terpyridine, L = phen (1,10-Phenanthroline), Me2phen (4,7-Dimethyl-1,10-phenanthroline), Me4phen (3,4,7,8-Tetramethyl-1,10-phenanthroline), Me2bpy (4,4′-Dimethyl-2–2′-dipyridyl)} for the chemoselective reduction of aldehydes to alcohols in aqueous ethanol and sodium formate as the hydride source. The reaction can be carried out efficiently in broad pH ranges, from pH 6 to 11. These catalysts are air stable, easy to prepare using commercially available starting materials, and are highly applicable for a wide range of substrates, such as electron-rich or deficient (hetero)arenes, halogens, phenols, alkoxy, ketones, esters, carboxylic acids, cyano, and nitro groups. Particularly, acid and hydroxy groups containing aldehydes were reduced successfully in basic and acidic reaction conditions, demonstrating the efficiency of the catalyst in a broad pH range with high conversion rates under microwave irradiation.
- Pandrala, Mallesh,Resendez, Angel,Malhotra, Sanjay V.
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p. 283 - 288
(2019/09/30)
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- Tris(pyrazolyl)borate Cobalt-Catalyzed Hydrogenation of C=O, C=C, and C=N Bonds: An Assistant Role of a Lewis Base
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The combination of tris(pyrazolyl)borate cobalt complexes and Lewis base is developed as an efficient catalyst precursor in the homogeneous hydrogenation. A broad substrate scope including carbonyls, alkenes, enamines, and imines is reduced with 60 atm of H2 at 60 °C. Mechanistic studies support the hydrogenation operates through a frustrated Lewis pair (FLP)-like reduction process. These results highlight the development of novel non-noble metal catalytic processes, when combined with the diverse small molecule activation chemistry associated with FLPs.
- Lin, Yang,Zhu, De-Ping,Du, Yi-Ran,Zhang, Rui,Zhang, Suo-Jiang,Xu, Bao-Hua
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supporting information
p. 2693 - 2698
(2019/04/25)
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- Manganese(I)-Catalyzed Transfer Hydrogenation and Acceptorless Dehydrogenative Condensation: Promotional Influence of the Uncoordinated N-Heterocycle
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The four bidentate manganese(I) complexes [(C5H4N-C5H3N-OH)Mn(CO)3Br] (1), [(C9H6N-C5H3N-OH)Mn(CO)3Br] (2), [(C8H5N2-C5H3N-OH)Mn(CO)3Br] (3), and [(C8H5N2-C5H3N-OCH3)Mn(CO)3Br] (4) were synthesized. These complexes were tested as catalysts for the transfer hydrogenation of ketones, and 3 showed the highest activity. The reactions proceeded well with 0.5 mol % of catalyst loading and 20 mol % of t-BuOK at 85 °C for 24 h. Furthermore, 3 was also used as a catalyst for the synthesis of primary alcohols via transfer hydrogenation of aldehydes and the synthesis of 1,2-disubstituted benzimidazoles and quinolines via acceptorless dehydrogenative condensations.
- Zhang, Chong,Hu, Bowen,Chen, Dafa,Xia, Haiping
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p. 3218 - 3226
(2019/09/13)
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- n-Butyllithium (1 mol %)-catalyzed Hydroboration of Aldehydes and Ketones with Pinacolborane
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A practical and efficient protocol for the hydroboration of aldehydes and ketones using a pinacolborane and alkyl lithium system is demonstrated. A systematic evaluation showed that 1 mol % n-butyllithium afforded catalyzed hydroboration of aldehydes and ketones in a short reaction time under ambient conditions. Excellent yield, functional group tolerance, short reaction time, low catalyst loading, and gram-scale synthesis are the salient features of the proposed protocol.
- Yang, Su Jin,Jaladi, Ashok Kumar,Kim, Jea Ho,Gundeti, Shankaraiah,An, Duk Keun
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- The reductive deaminative conversion of nitriles to alcohols using: Para -formaldehyde in aqueous solution
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We report herein, for the first time, the application of para-formaldehyde (pFA) to the reductive deamination of both aliphatic and aromatic nitriles in aqueous solution under transfer hydrogenation conditions. A broad range of primary alcohols have been synthesized selectively with very good to excellent yields under the optimized conditions. The study disclosed that the air-stable, inexpensive and commercially available catalyst [Ru(p-cymene)Cl2]2 acts as the catalyst precursor in this reaction, converting to other more active catalytic species in the presence of pFA, resulting in its degradation to CO2 and H2. Nitriles are also showed to play a dual role in this transformation, both as a substrate and as a ligand, where the dimeric catalyst structures convert to monomeric ones upon the coordination of nitrile molecules.
- Tavakoli, Ghazal,Prechtl, Martin H. G.
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p. 6092 - 6101
(2019/11/11)
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