- One-pot synthesis of γ,δ-unsaturated carbonyl compounds from allyl alcohols and vinyl or isopropenyl acetates catalyzed by [IrCl(cod)] 2
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One-pot synthesis of γ,δ-unsaturated carbonyl compounds from allyl alcohols and vinyl or isopropenyl acetates was achieved through in situ generation of allyl vinyl ethers by the action of the [IrCl(cod)]2 complex followed by Claisen rearrangement of the resulting ethers. For instance, the reaction of trans-2-methyl-3-phenyl-2-propen-1-ol with isopropenyl acetate in the presence of [IrCl(cod)]2 (1 mol %) and Cs2CO 3 (5 mol %) at 100 °C for 3 h followed by 140 °C for 15 h afforded 5-methyl-4-phenyl-5-hexen-2-one in 72% yield. When vinyl acetate was employed in place of isopropenyl acetate, 4-methyl-3-phenyl-4-pentenal was obtained in 83% yield.
- Morita, Masao,Sakaguchi, Satoshi,Ishii, Yasutaka
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- Diphenylboron perchlorate as an efficient catalyst for self- and cross-condensation reactions of aldehydes having α-active hydrogens
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Diphenylboron perchlorate very smoothly catalyzed self- and cross-condensation reactions of aldehydes at rt in nitroethane. The new catalyst provided novel behaviors owing to the characteristics of possessing a covalency in the boron-oxygen bond, compared with ionic perchlorates.
- Kiyooka, Syun-Ichi,Fujimoto, Hiroshi,Mishima, Masaaki,Kobayashi, Shinjiro,Uddin, Khabir Md.,Fujio, Mizue
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- Organoselenium-Catalyzed Regioselective C?H Pyridination of 1,3-Dienes and Alkenes
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An efficient approach for organoselenium-catalyzed regioselective C?H pyridination of 1,3-dienes to form pyridinium salts has been developed. This method was also successfully applied to direct C?H pyridination of alkenes. Fluoropyridinium reagents, or initially loaded pyridine derivatives, acted as pyridine sources in the pyridination reactions. The obtained pyridinium salts could be further converted under different conditions. This work is the first example of catalytic C-2 direct C?H functionalization of 1,3-dienes and the first case of organoselenium-catalyzed C?H pyridination.
- Liao, Lihao,Guo, Ruizhi,Zhao, Xiaodan
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- TEMPO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones in Ionic Liquid [bmim][PF6]
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(matrix presented) A simple and mild TEMPO-CuCl catalyzed aerobic oxidation of primary and secondary alcohols to the corresoponding aldehydes and ketones in ionic liquid [bmim][PF6] with no trace of overoxidation to carboxylic acids has been developed. The product can be isolated by a simple extraction with organic solvent, and the ionic liquid can be recycled or reused.
- Ansari, Imtiaz A.,Gree, Rene
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- Regioselective functionalization of pyrones: Facile synthesis of 6-styrylpyrones via KHMDS-mediated aldol condensation
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Herein, we disclose our efforts directed toward the synthesis of the kavalactone-based natural product penstyrylpyrone and other related 4-OMe-2-pyrones possessing diverse substituents at the 3-, 5-, and 7-positions. Further, a facile approach to access 6-styrylpyrones via the KHMDS-mediated regioselective aldol condensation of 2-pyrones is described with moderate substrate scope and good to high yields (58–80%). The utility of this methodology was exemplified by the stereoselective construction of desmethoxyyangonin, asnipyrone A, and asnipyrone B.
- Basu, Manas K.,Mukkanti, K.,Samala, Ramakrishna
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supporting information
(2022/01/03)
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- Pt-Catalyzed selective oxidation of alcohols to aldehydes with hydrogen peroxide using continuous flow reactors
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The oxidation of alcohols to aldehydes is a powerful reaction pathway for obtaining valuable fine chemicals used in pharmaceuticals and biologically active compounds. Although many oxidants can oxidize alcohols, only a few hydrogen peroxide oxidations can be employed to continuously synthesize aldehydes in high yields using a liquid-liquid two-phase flow reactor, despite the possibility of the application toward a safe and rapid multi-step synthesis. We herein report the continuous flow synthesis of (E)-cinnamaldehyde from (E)-cinnamyl alcohol in 95%-98% yields with 99% selectivity for over 5 days by the selective oxidation of hydrogen peroxide using a catalyst column in which Pt is dispersed in SiO2. The active species for the developed selective oxidation is found to be zero-valent Pt(0) from the X-ray photoelectron spectroscopy measurements of the Pt surface before and after the oxidation. Using Pt black diluted with SiO2as a catalyst to retain the Pt(0) species with the optimal substrate and H2O2introduction rate not only enhances the catalytic activity but also maintains the activity during the flow reaction. Optimizing the contact time of the substrate with Pt and H2O2using a flow reactor is important to proceed with the selective oxidation to prevent the catalytic H2O2decomposition.
- Kon, Yoshihiro,Nakashima, Takuya,Yada, Akira,Fujitani, Tadahiro,Onozawa, Shun-Ya,Kobayashi, Shū,Sato, Kazuhiko
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supporting information
p. 1115 - 1121
(2021/02/16)
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- PhIO-Mediated oxidative dethioacetalization/dethioketalization under water-free conditions
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Treatment of thioacetals and thioketals with iodosobenzene in anhydrous DCM conveniently afforded the corresponding carbonyl compounds in high yields under water-free conditions. The mechanistic studies indicate that this dethioacetalization/dethioketalization process does not need water and the oxygen of the carbonyl products comes from the hypervalent iodine reagent.
- Du, Yunfei,Ouyang, Yaxin,Wang, Xi,Wang, Xiaofan,Yu, Zhenyang,Zhao, Bingyue,Zhao, Kang
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- Rhodium-Catalyzed Regioselective Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes Using Formic Acid
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A rhodium-catalyzed hydroformylation of alkynes with formic acid was developed. The method provides α,β-unsaturated aldehydes in high yield and E-selectivity without the need to handle toxic CO gas.
- Fan, Chao,Hou, Jing,Chen, Yu-Jia,Ding, Kui-Ling,Zhou, Qi-Lin
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supporting information
p. 2074 - 2077
(2021/04/05)
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- Iron-Catalyzed ?±,?-Dehydrogenation of Carbonyl Compounds
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An iron-catalyzed α,β-dehydrogenation of carbonyl compounds was developed. A broad spectrum of carbonyls or analogues, such as aldehyde, ketone, lactone, lactam, amine, and alcohol, could be converted to their α,β-unsaturated counterparts in a simple one-step reaction with high yields.
- Zhang, Xiao-Wei,Jiang, Guo-Qing,Lei, Shu-Hui,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
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supporting information
p. 1611 - 1615
(2021/03/03)
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- Method for synthesizing alkyl olefin through coupling of double-bond carbon-hydrogen bond and saturated carbon-hydrogen bond
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The invention discloses a method for synthesizing alkyl olefin through coupling of a double-bond carbon-hydrogen bond and a saturated carbon-hydrogen bond. According to to the method, one-pot reactionis implemented on olefin and sulfoxide in the presence of ferric salt and hydrogen peroxide to generate alkyl olefin; in the method, sulfoxide is simultaneously used as a hydrocarbylation reagent anda solvent of olefin, and a reaction product is alkyl olefin from sulfoxide alkyl coupled with olefin carbon atoms, so that an olefin carbon chain is increased; the reaction conditions are mild, the selectivity is good, the yield is high, and industrial production is facilitated.
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Paragraph 0060-0069; 0093
(2021/02/10)
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- Method for hydrocarbylation synthesis of trisubstituted and tetrasubstituted olefins from non-terminal olefins
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The invention discloses a method for hydrocarbylation synthesis of trisubstituted and tetrasubstituted olefins from non-terminal olefins, wherein the method comprises the steps: carrying out hydrocarbylation reaction on the non-terminal olefins and sulfoxide in the presence of ferric salt and hydrogen peroxide, carrying out one-pot reaction on disubstituted non-terminal olefins to generate the trisubstituted olefins, and carrying out one-pot reaction on the trisubstituted non-terminal olefins to generate the tetrasubstituted olefins. In the method, sulfoxide is simultaneously used as a hydrocarbylation reagent and a solvent of olefins, and one more hydrocarbyl substituent is added to a reaction product compared with a double-bond carbon atom of a reactant, so that an olefin carbon chain isincreased; the reaction conditions are mild, the selectivity is good, the yield is high, and industrial production is facilitated.
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Paragraph 0054-0063; 0073-0075
(2021/02/06)
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- Asymmetric Nazarov Cyclizations of Unactivated Dienones by Hydrogen-Bond-Donor/Lewis Acid Co–Catalyzed, Enantioselective Proton-Transfer
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We report an enantioselective Nazarov cyclization catalyzed by chiral hydrogen-bond-donors in concert with silyl Lewis acids. The developed transformation provides access to tri-substituted cyclopentenones in high levels of enantioselectivity (up to 95% e.e.) from a variety of simple unactivated dienones. Kinetic and mechanistic studies are consistent with a reversible 4π-electrocyclization C?C bond-forming step followed by rate- and enantio-determining proton-transfer as the mode of catalysis. (Figure presented.).
- Metternich, Jan B.,Reiterer, Martin,Jacobsen, Eric N.
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p. 4092 - 4097
(2020/09/01)
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- Binuclear Pd(I)-Pd(I) Catalysis Assisted by Iodide Ligands for Selective Hydroformylation of Alkenes and Alkynes
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Since its discovery in 1938, hydroformylation has been thoroughly investigated and broadly applied in industry (>107 metric ton yearly). However, the ability to precisely control its regioselectivity with well-established Rh- or Co-catalysts has thus far proven elusive, thereby limiting access to many synthetically valuable aldehydes. Pd-catalysts represent an appealing alternative, yet their use remains sparse due to undesired side-processes. Here, we report a highly selective and exceptionally active catalyst system that is driven by a novel activation strategy and features a unique Pd(I)-Pd(I) mechanism, involving an iodide-assisted binuclear step to release the product. This method enables β-selective hydroformylation of a large range of alkenes and alkynes, including sensitive starting materials. Its utility is demonstrated in the synthesis of antiobesity drug Rimonabant and anti-HIV agent PNU-32945. In a broader context, the new mechanistic understanding enables the development of other carbonylation reactions of high importance to chemical industry.
- Zhang, Yang,Torker, Sebastian,Sigrist, Michel,Bregovi?, Nikola,Dydio, Pawe?
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supporting information
p. 18251 - 18265
(2020/11/02)
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- Dehydrogenative β-Arylation of Saturated Aldehydes Using Transient Directing Groups
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An unprecedented cross-dehydrogenative-coupling (CDC) reaction of saturated aldehyde β-C-H with arenes to form cinnamaldehydes via the cleavages of four C-H bonds has been developed. The reaction possesses complete E-stereoselectivity for the C=C double bond. The protocol is featured by atom and step economy, mild reaction conditions, and convenient operation.
- Zhang, Xing-Long,Pan, Gao-Fei,Zhu, Xue-Qing,Guo, Rui-Li,Gao, Ya-Ru,Wang, Yong-Qiang
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supporting information
p. 2731 - 2735
(2019/04/30)
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- Modular synthesis of (E)-cinnamaldehydes directly from allylarenes via a metal-free DDQ-mediated oxidative process
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An efficient synthesis of (E)-cinnamaldehydes by a metal-free DDQ-mediated oxidative transformation of allylarenes was developed. The protocol provides a practical method to prepare diverse (E)-cinnamaldehydes with broad functional group tolerance in good to excellent yields, including easy access to natural products randainal and geranyloxy sinapyl aldehyde from plant extracts. Finally, the mechanism of a single-electron transfer process was proposed.
- Xu, Ting-Ting,Jiang, Tao-Shan,Han, Xiao-Lan,Xu, Yuan-Hong,Qiao, Jin-Ping
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p. 5350 - 5358
(2018/08/03)
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- Inter- and intramolecular aldol reactions promiscuously catalyzed by a proline-based tautomerase
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The enzyme 4-oxalocrotonate tautomerase (4-OT), which in nature catalyzes a tautomerization step as part of a catabolic pathway for aromatic hydrocarbons, was found to promiscuously catalyze different types of aldol reactions. These include the self-condensation of propanal, the cross-coupling of propanal and benzaldehyde, the cross-coupling of propanal and pyruvate, and the intramolecular cyclizations of hexanedial and heptanedial. Mutation of the catalytic amino-terminal proline (P1A) greatly reduces 4-OT's aldolase activities, whereas mutation of another active site residue (F50A) strongly enhances 4-OT's aldolase activities, indicating that aldolization is an active site process. This catalytic promiscuity of 4-OT could be exploited as starting point to create tailor-made, artificial aldolases for challenging self- and cross-aldolizations.
- Rahimi, Mehran,Geertsema, Edzard M.,Miao, Yufeng,Van Der Meer, Jan-Ytzen,Van Den Bosch, Thea,De Haan, Pim,Zandvoort, Ellen,Poelarends, Gerrit J.
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supporting information
p. 2809 - 2816
(2017/04/03)
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- Poly(phosphoric acid) (PPA)-Promoted 5- exo -Cyclization of Iminium Ions Generated in Situ: A Facile Access to Functionalized Indene Derivatives
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A metal-free Bronsted acid promoted two-component reaction between cinnamaldehydes and sulfonamides is described. This cascade process provides a simple and atom-economical alternative synthesis of a range of functionalized indenes from easily available starting materials. The resulting N -indenylsulfonamides were readily converted into the corresponding indenylenamines or indanones.
- Zhu, Yi-Fan,Geng, Xin-Le,Guan, Yong-Hong,Teng, Wei,Fan, Xiaohui
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supporting information
p. 1821 - 1827
(2017/09/30)
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- Facile synthesis of indene and fluorene derivatives through AlCl3-catalyzed cyclization of in situ formed iminium ions
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A simple AlCl3-catalyzed condensation/cyclization cascade process between aldehydes and sulfonamide is reported, in which two new bonds and one five-membered ring are simultaneously formed with water as the byproduct. This method provides a rapid access to indenamine and 9-aminofluorene derivatives. Additionally, these products can be transformed into corresponding indanones and fluorenones under the developed conditions.
- Chen, Lei,Teng, Wei,Geng, Xin-Le,Zhu, Yi-Fan,Guan, Yong-Hong,Fan, Xiaohui
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- Peroxotantalate-Based Ionic Liquid Catalyzed Epoxidation of Allylic Alcohols with Hydrogen Peroxide
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The efficient and environmentally benign epoxidation of allylic alcohols has been attained by using new kinds of monomeric peroxotantalate anion-functionalized ionic liquids (ILs=[P4,4,4,n]3[Ta(O)3(η-O2)], P4,4,4,n=quaternary phosphonium cation, n=4, 8, and 14), which have been developed and their structures determined accordingly. This work revealed the parent anions of the ILs underwent structural transformation in the presence of H2O2. The formed active species exhibited excellent catalytic activity, with a turnover frequency for [P4,4,4,4]3[Ta(O)3(η-O2)] of up to 285 h?1, and satisfactory recyclability in the epoxidation of various allylic alcohols under very mild conditions by using only one equivalent of hydrogen peroxide as an oxidant. NMR studies showed the reaction was facilitated through a hydrogen-bonding mechanism, in which the peroxo group (O–O) of the peroxotantalate anion served as the hydrogen-bond acceptor and hydroxyl group in the allylic alcohols served as the hydrogen-bond donor. This work demonstrates that simple monomeric peroxotantalates can catalyze epoxidation of allylic alcohols efficiently.
- Ma, Wenbao,Chen, Chen,Kong, Kang,Dong, Qifeng,Li, Kun,Yuan, Mingming,Li, Difan,Hou, Zhenshan
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p. 7287 - 7296
(2017/05/31)
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- Selective rhodium-catalyzed hydroformylation of alkynes to α,β-unsaturated aldehydes with a tetraphosphoramidite ligand
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A tetraphosphoramidite ligand was successfully applied to a Rh-catalyzed hydroformylation of various symmetrical and unsymmetrical alkynes to afford corresponding α,β-unsaturated aldehyde products in good to excellent yields (up to 97% yield). Excellent chemo- and regioselectivities and high activities (up to 20 000 TON) were achieved. The corresponding α,β-unsaturated aldehyde products can be transformed into many useful and important organic molecules, such as indenamine derivatives and lukianol pyrroles. This great performance makes the hydroformylation of alkynes highly practical with great potential.
- Zhang, Zongpeng,Wang, Qian,Chen, Caiyou,Han, Zhengyu,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 3290 - 3293
(2016/07/13)
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- A TEMPO-free copper-catalyzed aerobic oxidation of alcohols
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The copper-catalyzed aerobic oxidation of primary and secondary alcohols without an external N-oxide co-oxidant is described. The catalyst system is composed of a Cu/diamine complex inspired by the enzyme tyrosinase, along with dimethylaminopyridine (DMAP) or N-methylimidazole (NMI). The Cu catalyst system works without 2,2,6,6-tetramethyl-l-piperidinoxyl (TEMPO) at ambient pressure and temperature, and displays activity for un-activated secondary alcohols, which remain a challenging substrate for catalytic aerobic systems. Our work underscores the importance of finding alternative mechanistic pathways for alcohol oxidation, which complement Cu/TEMPO systems, and demonstrate, in this case, a preference for the oxidation of activated secondary over primary alcohols.
- Xu, Boran,Lumb, Jean-Philip,Arndtsen, Bruce A.
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supporting information
p. 4208 - 4211
(2015/04/14)
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- NMO·TPB: A selectivity variation on the Ley-Griffith TPAP oxidation
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A non-hygroscopic tetraphenylborate salt of N-methylmorpholine-N-oxide (NMO) is reported (NMO·TPB), which modulates the standard Ley-Griffith oxidation such that benzylic and allylic alcohols are oxidised selectively. An attractive feature of this new protocol is that anhydrous conditions are not required for this selective tetra-n-propylammonium perruthenate (TPAP) oxidation, superseding the requirement of molecular sieves.
- Moore, Peter W.,Mirzayans, Paul M.,Williams, Craig M.
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supporting information
p. 3567 - 3571
(2015/03/04)
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- N,N,N′,N′-Tetramethylenediamine dioxide (TMEDAO2) facilitates atom economical/open atmosphere Ley-Griffith (TPAP) tandem oxidation-Wittig reactions
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N,N,N′,N′-Tetramethylethylenediamine dioxide (TMEDAO2) was explored as a more atom economical co-oxidant for the Ley-Griffith oxidation of alcohols to aldehydes. TMEDAO2 was found to selectivity oxidise benzylic and allylic alcohols in comparable yields to that of the standard Ley-Griffith co-oxidant (NMO). Importantly TMEDAO2 facilitated tandem Ley-Griffith-Wittig reactions with stabilised ylides, in good to excellent yields, without the requirement of anhydrous conditions.
- Read, Christopher D. G.,Moore, Peter W.,Williams, Craig M.
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supporting information
p. 4537 - 4540
(2015/09/15)
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- Oxidative cleavage of allyl ethers by an oxoammonium salt
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A method to oxidatively cleave allyl ethers to their corresponding aldehydes mediated by an oxoammonium salt is described. Using a biphasic solvent system and mild heating, cleavage proceeds readily, furnishing a variety of α,β-unsaturated aldehydes and ketones.
- Kelly, Christopher B.,Ovian, John M.,Cywar, Robin M.,Gosselin, Taylor R.,Wiles, Rebecca J.,Leadbeater, Nicholas E.
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p. 4255 - 4259
(2015/04/14)
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- Assembly of indenamine derivatives through in situ formed N-sulfonyliminium ion initiated cyclization
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An expedient route to structurally diverse indenamine derivatives through condensation of the readily accessible substituted cinnamylaldehydes and sulfonylamines under the catalysis of FeCl3 has been developed, featuring high efficiency in the generation of two bonds and one ring in a single-step and water as the only by-product. This journal is the Partner Organisations 2014.
- Fan, Xiaohui,Lv, Hao,Guan, Yong-Hong,Zhu, Hong-Bo,Cui, Xiao-Meng,Guo, Kun
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supporting information
p. 4119 - 4122
(2014/04/03)
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- Mesoporous Silicas as Versatile Supports to Tune the Palladium-Catalyzed Selective Aerobic Oxidation of Allylic Alcohols
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Surfactant templating offers a simple route to synthesize high-surface area silicas with ordered, tunable mesopore architectures. The use of these materials as versatile catalyst supports for palladium nanoparticles has been explored in the aerobic selective oxidation (selox) of allylic alcohols under mild conditions. Families of Pd/mesoporous silicas, synthesized through incipient wetness impregnation of SBA-15, SBA-16, and KIT-6, have been characterized by using nitrogen porosimetry, CO chemisorption, diffuse reflection infrared Fourier transform spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and high-resolution TEM and benchmarked in liquid phase allylic alcohol selox against a Pd/amorphous SiO2 standard. The transition from amorphous to two-dimensional parallel and three-dimensional interpenetrating porous silica networks conferred significant selox rate enhancements associated with higher surface densities of active palladium oxide sites. Dissolved oxygen was essential for insitu stabilization of palladium oxide, and thus maintenance of high activity on-stream, whereas selectivity to the desired aldehyde selox product over competing hydrogenolysis pathways was directed by using palladium metal.
- Parlett, Christopher M. A.,Bruce, Duncan W.,Hondow, Nicole S.,Newton, Mark A.,Lee, Adam F.,Wilson, Karen
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p. 939 - 950
(2013/06/04)
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- An excellent dual recycling strategy for the hypervalent iodine/nitroxyl radical mediated selective oxidation of alcohols to aldehydes and ketones
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Using a recyclable hypervalent iodine reagent 1, the authors have constructed versatile and green methods for the hypervalent iodine and nitroxyl radical-mediated selective oxidation of alcohols to aldehydes and ketones. The recyclable reagent 1 having a unique tetraphenyladamantane structure exhibited almost the same reactivity as the ordinary reagent, phenyliodine diacetate (PIDA), in the hypervalent iodine(iii)/2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-mediated oxidation. For recycling, the reagent 1 could be nearly quantitatively recovered as the reduced tetraiodide 2 by filtration after reaction completion, utilizing the insolubility of the formed 2 in a polar solvent, specifically, methanol. Based on the confirmed reactivity and excellent recycling operation of the reagent 1, the methodology has been further extended to a greener dual recycling strategy. By combining the recyclable iodine reagent 1 and silica-supported TEPMO catalyst, a variety of alcohols were effectively oxidized to the desired aldehydes, and the two types of used reagent and catalyst, the iodine 1 and immobilized TEMPO 5, could be separately recovered by an easy workup, and both repeatedly used without any loss of their original activities for at least four cycles.
- Dohi, Toshifumi,Fukushima, Kei-Ichiro,Kamitanaka, Tohru,Morimoto, Koji,Takenaga, Naoko,Kita, Yasuyuki
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experimental part
p. 1493 - 1501
(2012/06/18)
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- Neutral nazarov-type cyclization catalyzed by palladium(0)
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Joining the circle: The first Pd0 catalyzed Nazarov-type cyclization of diketoesters (see scheme) proceeds in 70 % to 95 % yield under strictly neutral pH conditions. Aryl substitution of the diketoesters is not required, so the reaction shows great versatility and can also proceed with aliphatic substrates. Copyright
- Shimada, Naoyuki,Stewart, Craig,Bow, William F.,Jolit, Anais,Wong, Kahoano,Zhou, Zhe,Tius, Marcus A.
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supporting information; experimental part
p. 5727 - 5729
(2012/08/07)
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- Nanocrystalline magnesium oxide stabilized palladium(0): An efficient reusable catalyst for room temperature selective aerobic oxidation of alcohols
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Nanocrystalline magnesium oxide-stabilized palladium(0) [NAP-Mg-Pd(0)], as an efficient catalytic system has been employed for the selective oxidation of alcohols using atmospheric oxygen as a green oxidant at room temperature. Various alcohols could be transformed into their corresponding aldehydes or ketones in good to excellent yields using a set of optimal conditions. NanoActive Magnesium Oxide Plus, [NAP-MgO] with its three-dimensional structure and well-defined shape acts as an excellent support for well dispersed palladium(0) nanoparticles. This catalyst can be recovered and reused for several cycles without any significant loss of catalytic activity.
- Layek, Keya,Maheswaran,Arundhathi,Kantam, M. Lakshmi,Bhargava, Suresh K.
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supporting information; experimental part
p. 606 - 616
(2011/04/25)
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- Facile synthesis of (E)-alkenyl aldehydes from allyl arenes or alkenes via Pd(II)-catalyzed direct oxygenation of allylic C-H bond
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Palladium-catalyzed oxygenation of allyl arenes or alkenes has been developed to produce (E)-alkenyl aldehydes with high yields. Allylic C-H bond cleavages occur under the mild conditions during this process. Mechanistic studies show that oxygen source is water.(Figure Presented)
- Chen, Huoji,Jiang, Huanfeng,Cai, Congbi,Dong, Jia,Fu, Wei
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supporting information; experimental part
p. 992 - 994
(2011/05/08)
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- Two-carbon homologation of aldehydes and ketones to α,β- unsaturated aldehydes
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Phosphonate reagents were developed for the two-carbon homologation of aldehydes or ketones to unbranched- or methyl-branched α,β- unsaturated aldehydes. The phosphonate reagents, diethyl methylformyl-2- phosphonate dimethylhydrazone and diethyl ethylformyl-2-phosphonate dimethylhydrazone, contained a protected aldehyde group instead of the usual ester group. A homologation cycle entailed condensation of the reagent with the starting aldehyde, followed by removal of the dimethylhydrazone protective group with a biphasic mixture of 1 M HCl and petroleum ether. This robust two-step process worked with a variety of aldehydes and ketones. Overall isolated yields of unsaturated aldehyde products ranged from 71% to 86% after the condensation and deprotection steps.
- Petroski, Richard J.,Vermillion, Karl,Cosse, Allard A.
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experimental part
p. 5062 - 5078
(2011/08/21)
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- Pd/C and NaBH4 in basic aqueous alcohol: An efficient system for an environmentally benign oxidation of alcohols
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We report the oxidation of a wide range of alcohols using an environmentally benign and economical process. The use of Pd/C heterogeneous catalysts along with NaBH4in aqueous ethanol or methanol and either K2CO3 or KOH as base at room temperature under molecular oxygen or air give the corresponding oxidation products. This protocol is versatile since it is capable of oxidizing alcohols to its desired carbonyl or carboxyl counterpart. Room temperature reaction in aqueous system and recyclability of the catalyst are among the advantages of this manipulation. These advantages make the process safe and cheaper rendering it favorable from both economic and environmental viewpoints. Georg Thieme Verlag Stuttgart New York.
- An, Gwangil,Ahn, Hyunseok,De Castro, Kathlia A.,Rhee, Hakjune
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experimental part
p. 477 - 485
(2010/06/13)
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- An organocatalytic asymmetric nazarov cyclization
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An organocatalytic asymmetric Nazarov cyclization of diketoesters that proceeds by means of a dual activation mechanism has been developed. Screening of a number of catalysts led to a new thiourea that incorporates a primary amino group. The method gives rise to cyclic products with two adjacent quaternary asymmetric carbon atoms, one of which is an all-carbon stereocenter, with complete or nearly complete diastereoselectivity and in high or very high enantiomeric excess. A brief and very convenient synthesis of the acyclic diketoester starting materials through nucleophilic addition to a ketene is also described.
- Basak, Ashok K.,Shimada, Naoyuki,Bow, William F.,Vicic, David A.,Tius, Marcus A.
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supporting information; experimental part
p. 8266 - 8267
(2010/08/04)
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- Controlled and chemoselective reduction of secondary amides
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This communication describes a metal-free methodology involving an efficient and controlled reduction of secondary amides to imines, aldehydes, and amines in good to excellent yields under ambient pressure and temperature. The process includes a chemoselective activation of a secondary amide with triflic anhydride in the presence of 2-fluoropyridine. The electrophilic activated amide can then be reduced to the corresponding iminium using triethylsilane, a cheap, rather inert, and commercially available reagent. Imines can be isolated after a basic workup or readily transformed to the aldehydes following an acidic workup. The amine moiety can be accessed via a sequential reductive amination by the addition of silane and Hantzsch ester hydride in a one-pot reaction. Moreover, this reduction tolerates various functional groups that are usually reactive under reductive conditions and is very selective to secondary amides.
- Pelletier, Guillaume,Bechara, William S.,Charette, Andre B.
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supporting information; experimental part
p. 12817 - 12819
(2010/11/05)
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- Stereoselective olefination reactions promoted by Rieke manganese
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A study of the advantages of using manganese, an inexpensive and nontoxic metal, to perform stereoselective β-elimination reactions and to promote sequential olefination reactions of aldehydes to obtain α,β- unsaturated esters and amides is presented. Various elimination reactions, all of them characterized by occurring with complete stereoselectivity and in high yields, were performed using active manganese (Mn*) as metalating agent. This ability of manganese has been applied to develop a novel and direct synthesis of (E)-α,β-unsaturated esters or amides and (Z)-α,β-unsaturated α-halo esters and α-choroamides through a Mn*-mediated sequential olefination protocol of aldehydes with dichloro esters or amides and trihalo esters or trichloroamides, respectively. Georg Thieme Verlag Stuttgart.
- Concellon, Jose M.,Rodriguez-Solla, Humberto,Del Amo, Vicente,Diaz, Pamela
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experimental part
p. 2634 - 2645
(2009/12/06)
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- Traceless sulfone linker cleavage triggered by ozonolysis: solid-phase synthesis of diverse α-β-unsaturated carbonyl compounds
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The highly efficient and convenient protocol to prepare diverse α,β-unsaturated aldehydes, ketones, and acids via the parallel solid-phase synthesis is developed. The key sulfone linker cleavage strategy is performed by ozonolysis to generate a carbonyl moiety followed by base-mediated polymer-bound sulfinate elimination to release our desired molecules from the resin. All α,β-unsaturated carbonyl compounds are prepared in good purities and yields without further purification.
- Chang, Yi-Fan,Jiang, Yi-Rui,Cheng, Wei-Chieh
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p. 543 - 547
(2008/04/13)
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- New phosphonate reagents for aldehyde homologation
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New phosphonate reagents were developed for the two-carbon homologation of aldehydes to unbranched or methyl-branched unsaturated aldehydes. The phosphonate reagents, diethyl methylformylphosphonate dimethylhydrazone and diethyl ethylformyl-2-phosphonate dimethylhydrazone, contained a protected aldehyde group instead of the usual ester group. A homologation cycle entailed condensation of the reagent with the starting aldehyde, followed by removal of the dimethylhydrazone protective group with a biphasic mixture of 1 M HCl and petroleum ether. This robust two-step process worked with aliphatic, α,β-unsaturated and aromatic aldehydes. Isolated yields for the condensation step ranged from 77% to 89%, and yields for the deprotection step ranged from 81% to 96%. Copyright Taylor & Francis Group, LLC.
- Petroski, Richard J.
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p. 3841 - 3854
(2008/02/10)
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- Environmentally benign oxidation reaction of benzylic and allylic alcohols to carbonyl compounds using Pd/C with sodium borohydride
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Pd/C catalyst in aqueous alcohol with molecular oxygen, sodium borohydride, and potassium carbonate efficiently oxidized benzylic and allylic alcohols. The use of a reducing reagent, sodium borohydride, for the reactivation of active sites of the Pd surface proved to be remarkable. The utilization of room temperature reaction condition and aqueous alcohol solvent as well as the recyclability of Pd/C makes this manipulation very interesting from an economic and environmental perspective. Georg Thieme Verlag Stuttgart.
- An, Gwangil,Lim, Minkyung,Chun, Kwon-Soo,Rhee, Hakjune
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- The role of imine-enamine tautomerism in effecting cross-aldol condensations
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An indirect method to effect cross-aldol coupling of two nonequivalent enolizable aldehydes is reported that involves initial conversion of one aldehyde to an imine derivative possessing an N-3° alkyl substituent. In sharp contrast to the related couplings (e.g., the use of α-lithiated imines at low temperature), condensation between the imine and several representative aldehydes occurs readily at ambient temperature in the presence of a catalytic amount of cobalt(II) chloride.
- Babler, James H.,Atwood, Matthew C.,Freaney, Jonathan E.,Viszlay, Anthony R.
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p. 7665 - 7667
(2008/03/30)
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- Sequential reactions promoted by manganese: Completely stereoselective synthesis of (E)-α,β-unsaturated amides, ketones, aldehydes, and carboxylic acids
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(Chemical Equation Presented) A complete E-selective synthesis of α,β-unsaturated amides through a sequential reaction of a range of dichloroamides with a variety of aldehydes promoted by Rieke manganese (Mn*) is reported. A mechanism based on a sequential aldol-type reaction and a completely stereoselective β-elimination is proposed to explain these results. The unsaturated amides obtained are readily and efficiently transformed into α,β-unsaturated ketones, aldehydes, or carboxylic acids without loss of the diastereoisomeric purity of the C-C double bond.
- Concellon, Jose M.,Rodriguez-Solla, Humberto,Diaz, Pamela
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p. 7974 - 7979
(2008/02/13)
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- Tuning the oxidation properties of vanadium(V) through ligand stoichiometry
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Vanadium(V) (5 mol %) and hydroxamic acid ligand (45 mol %) were found to promote the selective tert-butyl hydroperoxide-mediated oxidation of allylic and propargylic alcohols to the corresponding aldehydes and ketones.
- Zeng, Wei,Ballard, T. Eric,Melander, Christian
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p. 5923 - 5926
(2007/10/03)
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- A general route to α-alkyl (E)-α,β-unsaturated aldehydes
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Bis(trimethylsilyl)-tert-butylaldimines 3 react with aldehydes in the presence of zinc bromide at room temperature to give, after hydrolysis, the desired α-alkyl α,β-ethylenic aldehydes in good yield and with very high E stereoselectivity. The reaction was believed to proceed via the α-silyl β-siloxyimines 4.
- Lahmar, Nour,Aatar, Jamaa,Ayed, Ta?cir Ben,Amri, Hassen,Bellassoued, Moncef
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p. 3018 - 3026
(2007/10/03)
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- Preparation and deprotection of aldehyde dimethylhydrazones
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Aldehydes were conveniently protected as dimethylhydrazones by stirring a mixture of the aldehyde, N,N-dimethylhydrazine, anhydrous magnesium sulfate, and dichloromethane at room temperature. Azeotropic removal of water, formed during the course of the reaction, was not required because anhydrous magnesium sulfate functions as a water scavenger. Deprotection of aldehyde dimethylhydrazones was accomplished by stirring a mixture of the aldehyde dimethylhydrazone and aqueous glyoxylic acid at room temperature. The reaction time for the preparation and deprotection of aldehyde dimethylhydrazones varied with the structure of the aldehyde. Copyright Taylor & Francis Group, LLC.
- Petroski, Richard J.
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p. 1727 - 1734
(2007/10/03)
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- Tetraalkylammonium and 1,3-dialkylimidazolium salts with fluorinated anions as recoverable phase-transfer catalysts in solid base-promoted cross-aldol condensations
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Tetraalkylammonium and 1,3-dialkylimidazolium tetrafluoroborates and hexafluorophosphates were employed for the first time as recoverable phase-transfer catalysts in multiphase reactions of CH-acids, in particular in solid base-pro-moted cross-aldol condensations. The catalysts retained their catalytic activity over several reaction cycles.
- Kryshtal, Galina V.,Zhdankina, Galina M.,Zlotin, Sergei G.
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p. 2822 - 2827
(2007/10/03)
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- Oxidative coupling of benzenes with α,β-unsaturated aldehydes by the Pd(OAc)2/molybdovanadophosphoric acid/O2 system
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The oxidative coupling reaction of benzene with an α,β- unsaturated aldehyde was examined by the combined catalytic system of Pd(OAc)2 with molybdovanadophosphoric acid (HPMoV) under atmospheric dioxygen. Thus, the reaction of benzene with acrolein under dioxygen (1 atm) by the use of catalytic amounts of Pd(OAc)2 and H4PMo 11VO40·26H2O in the presence of dibenzoylmethane as a ligand in propionic acid at 90 °C for 1.5 h afforded cinnamaldehyde in 59% yield and β-phenylcinnamaldehyde in 5% yield. This catalytic system was extended to the direct oxidative coupling through the C-H bond activation of various arenes with acrolein and methacrolein.
- Yamada, Tomoyuki,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 5471 - 5474
(2008/04/18)
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- Direct preparation of monoarylidene derivatives of aldehydes and enolizable ketones with DIMCARB
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(Matrix presented) Aryl α,β-unsaturated ketones and aldehydes were synthesized, in moderate to excellent yields, with use of dimethylammonium dimethyl carbamate (DIMCARB) as a recyclable reaction medium and as a catalyst.
- Kreher, Ulf P.,Rosamilia, Anthony E.,Raston, Colin L.,Scott, Janet L.,Strauss, Christopher R.
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p. 3107 - 3110
(2007/10/03)
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- An Efficient Aerobic Oxidation of Alcohols to Aldehydes and Ketones with TEMPO/Ceric Ammonium Nitrate as Catalysts
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Secondary benzylic alcohols with an alkyl chain are oxidized faster than simple benzyl alcohols. However the reaction time is prolonged, when the alkyl chain is replaced by a bulky phenyl ring such as benzhydrol and 9-hydroxyfluorene. All the benzyl and benzylic alcohols give yields >90%. Allylic alcohols without steric hindrance react faster to give excellent yield (>80%). The present method is superior to others currently available due to its relatively short reaction times and excellent yields.
- Kim, Sung Soo,Jung, Hyun Chul
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p. 2135 - 2137
(2007/10/03)
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- Chemoselective oxidation of alcohols to aldehydes and ketones by iodosobenzene/(salen) chromium complex
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Various benzylic and allylic alcohols were selectively oxidized to their corresponding aldehydes and ketones by a new Cr(III)(salen) complex I as the catalyst and PhIO as terminal oxidant. The oxidation requires relatively shorter reaction time and produces excellent yields.
- Kim, Sung Soo,Kim, Dong Won
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p. 1391 - 1394
(2007/10/03)
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- A Mild and Efficient Oxidation of Alcohols to Ketones with Iodosobenzene/(Salen) Manganese Complex
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An excellent method for the chemoselective oxidation of alcohols to ketones with C6H5IO catalyzed by (salen) manganese/4A MS in CH3CN has been devised. The reported procedure is fast, simple, and the yields are excellent (> 95%) in most cases.
- Kim, Sung Soo,Borisova, Galina
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p. 3961 - 3967
(2007/10/03)
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- Practical Os/Cu-cocatalyzed air oxidation of allyl and benzyl alcohols at room temperature and atmospheric pressure
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(equation presented) A new protocol for the oxidation of primary and secondary allyl and benzyl alcohols at room temperature and using 1 atm of air is described. The procedure uses low loadings of copper salts and osmium tetroxide, which is activated with quinuclidine and prereduced with an alkene. Chemoselectivity for allyl and benzyl alcohols is very high, no overoxidation is observed, and the reaction takes place under neutral conditions.
- Muldoon, John,Brown, Seth N.
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p. 1043 - 1045
(2007/10/03)
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