- Stereo- and Regioselective 1,3-Dipolar Cycloaddition of the Stable Ninhydrin-Derived Azomethine Ylide to Cyclopropenes: Trapping of Unstable Cyclopropene Dipolarophiles
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A stereo- and regioselective 1,3-dipolar cycloaddition of the stable ninhydrin-derived azomethine ylide [2-(3,4-dihydro-2H-pyrrolium-1-yl)-1-oxo-1H-inden-3-olate, DHPO] to differently substituted cyclopropenes has been established. As a result, an efficient synthetic protocol was developed for the preparation of biologically relevant spiro[cyclopropa[a]pyrrolizine-2,2′-indene] derivatives. DHPO has proved to be an effective trap for such highly reactive and unstable substrates as parent cyclopropene, 1-methylcyclopropene, 1-phenylcyclopropene, and 1-halo-2-phenylcyclopropenes. It has also been found that 3-nitro-1,2-diphenylcyclopropene undergoes a nucleophilic substitution reaction in alcohols and thiols to afford 3-alkoxy- and 3-arylthio-substituted 1,2-diphenylcyclopropenes, which can be captured as corresponding 1,3-dipolar cycloadducts in the presence of DHPO. These new approaches provide a straightforward strategy for the synthesis of functionally substituted cyclopropa[a]pyrrolizine derivatives. The factors governing regio- and stereoselectivity have been revealed by means of quantum mechanical calculations (M11 density functional theory), including previously unreported Nylide-Hcyclopropene second-orbital interactions. The outcome of this work contributes to the study of 1,3-dipolar cycloaddition, as well as enriches chemistry of cyclopropenes and methods for the construction of polycyclic compounds with cyclopropane fragments.
- Filatov, Alexander S.,Wang, Siqi,Khoroshilova, Olesya V.,Lozovskiy, Stanislav V.,Larina, Anna G.,Boitsov, Vitali M.,Stepakov, Alexander V.
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Read Online
- A stereoselective synthetic route to (Z)-α-stannyl-α,β-unsaturated aldehydes
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Acetylenic stannanes 1 react with Cp2Zr(H)Cl (Cp = η5-C5H5) and CO to give acylzirconocene chloride derivatives 2, which are trapped with dilute HCl to afford (Z)-α-stannyl-α,β-unsaturated aldehydes 3.
- Zhong,Xiong,Huang
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Read Online
- Carbocyclic ring expansions with alkyne and carbene sources mediated by nickel(0) complexes: Structure of the critical organonickel intermediates
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Experimental evidence is assessed concerning the nature of organonickel intermediates involved in the cyclotrimerization and the cyclotetramerization of alkynes, as well as the cross-oligomerization of alkynes with carbene sources, as mediated by nickel(0) complexes. In the former processes a sequential series of nickelacycloalkapolyenes are the productive intermediates and in the latter cross-oligomerizations nickel(0)-carbene complexes themselves are critical precursors to the ultimately generated carbocycles.
- Eisch, John J.,Aradi, Allen A.,Lucarelli, Michael A.,Qian, Yun
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Read Online
- Palladium-catalyzed ring-opening alkynylation of cyclopropenones
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N-Heterocyclic carbene-palladium catalysts are used to promote addition/ring opening of cyclopropenones with terminal alkynes. The ring-opening alkynylation affords alkenyl alkynyl ketones in good yields. For reactions with propargylic esters having an ar
- Matsuda, Takanori,Sakurai, Yusuke
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Read Online
- Cross β-arylmethylation of alcohols catalysed by recyclable Ti-Pd alloys not requiring pre-activation
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Ti-Pd alloy catalysts were developed for the cross β-arylmethylation between arylmethylalcohols and different primary alcohols via a hydrogen autotransfer mechanism. The alloy catalysts could be reused multiple times without the need for pre-activation. Analysis of the reaction solution by inductively coupled plasma atomic absorption spectroscopy indicated that only a minimal amount of Ti and no Pd was leached from the catalyst.
- Utsunomiya, Masayoshi,Kondo, Ryota,Oshima, Toshinori,Safumi, Masatoshi,Suzuki, Takeyuki,Obora, Yasushi
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supporting information
p. 5139 - 5142
(2021/05/31)
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- Complex Polyheterocycles and the Stereochemical Reassignment of Pileamartine A via Aza-Heck Triggered Aryl C-H Functionalization Cascades
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Structurally complex benzo- and spiro-fused N-polyheterocycles can be accessed via intramolecular Pd(0)-catalyzed alkene 1,2-aminoarylation reactions. The method uses N-(pentafluorobenzoyloxy)carbamates as the initiating motif, and this allows aza-Heck-type alkene amino-palladation in advance of C-H palladation of the aromatic component. The chemistry is showcased in the first total synthesis of the complex alkaloid (+)-pileamartine A, which has resulted in the reassignment of its absolute stereochemistry.
- Bower, John F.,Caiger, Lewis,García-Cárceles, Javier,Hazelden, Ian R.,Jones, Benjamin T.,Langer, Thomas,Lewis, Richard J.
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supporting information
p. 15593 - 15598
(2021/10/12)
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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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- 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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- Tuning the Selectivity of Palladium Catalysts for Hydroformylation and Semihydrogenation of Alkynes: Experimental and Mechanistic Studies
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Here, we describe a selective palladium catalyst system for chemodivergent functionalization of alkynes with syngas. In the presence of an advanced ligand L2 bearing 2-pyridyl substituent as a built-in base, either hydroformylation or semihydrogenation of diverse alkynes occurs with high chemo- and stereoselectivity under comparable conditions. Mechanistic studies, including density functional theory (DFT) calculations, kinetic analysis, and control experiments, revealed that the strength and concentration of acidic cocatalysts play a decisive role in controlling the chemoselectivity. DFT studies disclosed that ligand L2 not only promotes heterolytic activation of hydrogen similar to frustrated Lewis pair (FLP) systems in the hydrogenolysis step for hydroformylation but also suppresses CO coordination to promote semihydrogenation under strong acid conditions. This switchable selectivity provides a strategy to design new catalysts for desired products.
- Beller, Matthias,Ge, Yao,Jackstell, Ralf,Jiao, Haijun,Liu, Jiawang,Wei, Duo,Wei, Zhihong,Yang, Ji
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p. 12167 - 12181
(2020/11/27)
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- Stereo-controlledanti-hydromagnesiation of aryl alkynes by magnesium hydrides
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A concise protocol foranti-hydromagnesiation of aryl alkynes was established using 1?:?1 molar combination of sodium hydride (NaH) and magnesium iodide (MgI2) without the aid of any transition metal catalysts. The resulting alkenylmagnesium intermediates could be trapped with a series of electrophiles, thus providing facile accesses to stereochemically well-defined functionalized alkenes. Mechanistic studies by experimental and theoretical approaches imply that polar hydride addition from magnesium hydride (MgH2) is responsible for the process.
- Chiba, Shunsuke,Li, Yihang,Ong, Derek Yiren,Pang, Jia Hao,Takita, Ryo,Wang, Bin,Watanabe, Kohei
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p. 5267 - 5272
(2020/06/04)
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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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- Porous organic polymer supported rhodium as a heterogeneous catalyst for hydroformylation of alkynes to α,β-unsaturated aldehydes
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A new porous organic polymer supported rhodium catalyst (Rh/POL-BINAPa&PPh3) has been developed for the hydroformylation of various alkynes to afford the corresponding α,β-unsaturated aldehydes with high chem- and stereoselectivity, excellent catalytic activity and good reusability (10 cycles). The heterogeneous catalyst exhibited more catalytic activity than the comparable homogeneous Rh/BINAPa/PPh3 system.
- Liang, Zuyu,Chen, Jianbin,Chen, Xin,Zhang, Kai,Lv, Jinhe,Zhao, Haowen,Zhang, Guoying,Xie, Congxia,Zong, Lingbo,Jia, Xiaofei
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supporting information
p. 13721 - 13724
(2019/11/19)
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- Cis-cinnamic acid analogue, gravitropism modifier (by machine translation)
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[Problem] cinnamic acid or cinnamic acid analogue comprising adjusting agent gravitropism cis. [Solution] cinnamic acid and/or cinnamic acid as an active ingredient to adjust gravitropism cis edge agents, cinnamic acid edge is, for example obtained by reacting compounds of the following formula. (In the formula, R is a phenyl group. )Figure 6 [drawing] (by machine translation)
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Paragraph 0142-0143
(2019/11/30)
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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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- Highly-functionalized arene synthesis based on palladium on carbon-catalyzed aqueous dehydrogenation of cyclohexadienes and cyclohexenes
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Transition metal-catalyzed dehydrogenation is a clean oxidation method requiring no additional oxidants. We have accomplished a heterogeneous Pd/C-catalyzed aqueous dehydrogenation of 1,4-cyclohexadienes and cyclohexenes to give the corresponding highly-functionalized arenes. Furthermore, various arenes could be efficiently constructed in a one-pot manner via a Diels-Alder reaction and the following dehydrogenation.
- Yasukawa, Naoki,Yokoyama, Hiroki,Masuda, Masahiro,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 1213 - 1217
(2018/03/28)
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- Heck transformations of biological compounds catalyzed by phosphine-free palladium
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The development and optimization of synthetic methods leading to functionalized biologically active compounds is described. Two alternative pathways based on Heck-type reactions, employing iodobenzene or phenylboronic acid, were elaborated for the arylation of eugenol and estragole. Cinnamyl alcohol was efficiently transformed to saturated arylated aldehydes in reaction with iodobenzene using the tandem arylation/isomerization sequential process. The arylation of cinnamyl alcohol with phenylboronic acid mainly gave unsaturated alcohol, while the yield of saturated aldehyde was much lower. Catalytic reactions were carried out using simple, phosphine-free palladium precursors and water as a cosolvent, following green chemistry rules as much as possible.
- Tarnowicz-Ligus, Stanis?awa,Trzeciak, Anna M.
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supporting information
(2018/09/10)
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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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- Oxygenation of Simple Olefins through Selective Allylic C?C Bond Cleavage: A Direct Approach to Cinnamyl Aldehydes
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A novel metal-free allylic C?C σ-bond cleavage of simple olefins to give valuable cinnamyl aldehydes is reported. 1,2-Aryl or alkyl migration through allylic C?C bond cleavage occurs in this transformation, which is assisted by an alkyl azide reagent. This method enables O-atom incorporation into simple unfunctionalized olefins to construct cinnamyl aldehydes. The reaction features simple hydrocarbon substrates, metal-free conditions, and high regio- and stereoselectivity.
- Liu, Jianzhong,Wen, Xiaojin,Qin, Chong,Li, Xinyao,Luo, Xiao,Sun, Ao,Zhu, Bencong,Song, Song,Jiao, Ning
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p. 11940 - 11944
(2017/09/20)
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- CIS CINNAMIC ACID ANALOG AND GRAVITROPISM MODIFIER
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PROBLEM TO BE SOLVED: To provide a gravitropism modifier having effects on creeping property of plants or sugar content of fruits. SOLUTION: There is provided a gravitropism modifier containing cis cinnamic acid and/or a cinnamic acid analog represented by the formula (1) as active ingredients. (1), where A is cyclic hydrocarbon which may have a substituent, X is a bound or a C1 to 5 substituted or unsubstituted hydrocarbon chain, R1 is H, a hydroxyl group, an alkali earth metal salt or the like, R2 is a bond or a C1 to 5 substituted or unsubstituted hydrocarbon chain and R3 and R4 are H or together form C5 to 8 cyclic hydrocarbon. SELECTED DRAWING: Figure 6 COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0142; 0143
(2017/06/02)
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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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- Systematic methodology for the development of biocatalytic hydrogen-borrowing cascades: Application to the synthesis of chiral α-substituted carboxylic acids from α-substituted α,β-unsaturated aldehydes
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Ene-reductases (ERs) are flavin dependent enzymes that catalyze the asymmetric reduction of activated carbon-carbon double bonds. In particular, α,β-unsaturated carbonyl compounds (e.g. enals and enones) as well as nitroalkenes are rapidly reduced. Conversely, α,β-unsaturated esters are poorly accepted substrates whereas free carboxylic acids are not converted at all. The only exceptions are α,β-unsaturated diacids, diesters as well as esters bearing an electron-withdrawing group in α- or β-position. Here, we present an alternative approach that has a general applicability for directly obtaining diverse chiral α-substituted carboxylic acids. This approach combines two enzyme classes, namely ERs and aldehyde dehydrogenases (Ald-DHs), in a concurrent reductive-oxidative biocatalytic cascade. This strategy has several advantages as the starting material is an α-substituted α,β-unsaturated aldehyde, a class of compounds extremely reactive for the reduction of the alkene moiety. Furthermore no external hydride source from a sacrificial substrate (e.g. glucose, formate) is required since the hydride for the first reductive step is liberated in the second oxidative step. Such a process is defined as a hydrogen-borrowing cascade. This methodology has wide applicability as it was successfully applied to the synthesis of chiral substituted hydrocinnamic acids, aliphatic acids, heterocycles and even acetylated amino acids with elevated yield, chemo- and stereo-selectivity. A systematic methodology for optimizing the hydrogen-borrowing two-enzyme synthesis of α-chiral substituted carboxylic acids was developed. This systematic methodology has general applicability for the development of diverse hydrogen-borrowing processes that possess the highest atom efficiency and the lowest environmental impact. This journal is
- Knaus, Tanja,Mutti, Francesco G.,Humphreys, Luke D.,Turner, Nicholas J.,Scrutton, Nigel S.
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supporting information
p. 223 - 233
(2015/02/19)
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- Bismuth-substituted "sandwich" type polyoxometalate catalyst for activation of peroxide: Umpolung of the peroxo intermediate and change of chemoselectivity
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The epoxidation of alkenes with peroxides by WVI, MoVI, VV, and TiIV compounds is well established, and it is well accepted that the active intermediate peroxo species are electrophilic toward nucleophilic substrates. Polyoxotungstates, for example, those of the "sandwich" structure, [WZn(TM-L)2(ZnW9O34)2]q- in which TM = transition metal and L = H2O, have in the past been found to be excellent epoxidation catalysts. It has now been found that substituting the Lewis basic BiIII into the terminal position of the "sandwich" polyoxometalate structure to yield [Zn2BiIII2(ZnW9O34)2]14- leads to an apparent umpolung of the peroxo species and formation of a nucleophilic peroxo intermediate. There are two lines of evidence that support the formation of a reactive nucleophilic peroxo intermediate: (1) More electrophilic sulfoxides are more reactive than more nucleophilic sulfides, and (2) nonfunctionalized aliphatic alkenes and dienes showed ene type reactivity rather than epoxidation pointing toward "dark" formation of singlet oxygen from the nucleophilic intermediate peroxo species. Allylic alcohols reacted much faster than alkenes but showed chemoselectivity toward C-H bond activation of the alcohol and formation of aldehydes or ketones rather than epoxidation. This explained via alkoxide formation at the BiIII center followed by oxidative β-elimination.
- Amanchi, Srinivasa Rao,Khenkin, Alexander M.,Diskin-Posner, Yael,Neumann, Ronny
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p. 3336 - 3341
(2015/06/16)
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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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- Palladium-catalyzed dehydrogenative β-arylation of simple saturated carbonyls by aryl halides
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(Chemical Equation Presented) A versatile palladium-catalyzed synthesis of highly substituted α,β-unsaturated carbonyl compounds has been developed. In contrast to the known Heck-type coupling reaction of unsaturated carbonyl compounds with aryl halides, the present methodology allows the use of stable and readily available saturated carbonyl compounds as the alkene source. In addition, the reaction proceeds well with low catalyst loadings and does not require any expensive metal oxidants or ligands. A variety of saturated aldehydes, ketones, and esters are compatible for the reaction with aryl halides under the developed reaction conditions to afford α,β-unsaturated carbonyl compounds in good to excellent yields. A possible reaction mechanism involves a palladium-catalyzed dehydrogenation followed by Heck-type cross couplings.
- Gandeepan, Parthasarathy,Rajamalli,Cheng, Chien-Hong
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p. 4485 - 4489
(2015/01/09)
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- Synthesis of α,β-unsaturated aldehydes based on a one-pot phase-switch dehydrogenative cross-coupling of primary alcohols
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An efficient one-pot ruthenium-catalyzed hydrogen-transfer strategy for a direct access to α,β-unsaturated aldehydes has been developed. The employment of enolates prepared in situ from alcohols avoided handling unstable aldehydes and provided a very appealing route to different cinnamaldehydes substituted in position 2. A silica-grafted amine was used as phase-switch tag leading to a selective one-pot process in favor of cross-dehydrogenative coupling products.
- Mura, Manuel G.,De Luca, Lidia,Taddei, Maurizio,Williams, Jonathan M. J.,Porcheddu, Andrea
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supporting information
p. 2586 - 2589
(2014/06/09)
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- Rhodium-catalyzed hydroformylation of alkynes employing a self-assembling ligand system
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Hydroformylation of alkynes is an underdeveloped atom-economic and redox-neutral method to prepare enals. Applying a new electron poor self-assembling ligand system provides the first general rhodium-catalyst for the chemo- and stereoselective hydroformylation of dialkyl- as well as diaryl-substituted alkynes to furnish enals in excellent chemo- and stereoselectivity.
- Agabekov, Vladislav,Seiche, Wolfgang,Breit, Bernhard
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p. 2418 - 2422
(2013/07/11)
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- Selective palladium-catalyzed hydroformylation of alkynes to α,β-Unsaturated Aldehydes
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Atom-efficient: A selective palladium catalyst system is used for the hydroformylation of alkynes (see picture). In this syngas reaction, various alkynes were smoothly transformed to synthetically interesting α,β-unsaturated aldehydes in good yields with high regio- and stereoselectivity. Copyright
- Fang, Xianjie,Zhang, Min,Jackstell, Ralf,Beller, Matthias
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p. 4645 - 4649
(2013/05/22)
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- Iron-catalyzed chemo- and stereoselective hydromagnesiation of diarylalkynes and diynes
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Diarylalkynes are chemo- and stereoselectively hydromagnesiated in high yields at room temperature with an iron species generated in situ from FeCl 2and EtMgBr. Functional groups such as bromide, iodide, amine, phenoxide, and alkene are well tolerated. Under similar conditions, diynes are chemo-, regio-, and stereoselectively hydromagnesiated. The resulting alkenylmagnesium compounds are a platform for further functionalization as a one-pot reaction.
- Ilies, Laurean,Yoshida, Takumi,Nakamura, Eiichi
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supporting information
p. 16951 - 16954,4
(2020/09/02)
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- Ruthenium-catalyzed aldehyde functionality reshuffle: Selective synthesis of E-2-arylcinnamaldehydes from E-β-bromostyrenes and aryl aldehydes
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A new concept for highly selective synthesis of E-2-arylcinnamaldehydes has been developed via a formal arylformylation of E-β-bromostyrenes with readily available aryl aldehydes. This strategy involves an overall reshuffle of the aldehyde functionality with a loss of hydrogen bromide.
- Wang, Ping,Rao, Honghua,Zhou, Feng,Li, Chao-Jun,Hua, Ruimao
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supporting information
p. 16468 - 16471,4
(2020/09/15)
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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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- REGENERATION OF A HYDROFORMYLATION CATALYST DURING HYDROFORMYLATION
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A method for hydroformylating or hydrocarbonylating a substrate having a carbon-carbon double or triple bond or both is described. The method comprises exposing the substrate to a hydroformylation catalyst under an atmosphere comprising carbon monoxide and hydrogen in the presence of a regeneration reagent so as to form a product. The regeneration reagent is such that it is capable of at least partially reversing poisoning of the hydroformylation catalyst by a diene or an alkyne or both.
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Page/Page column 16-17
(2011/04/14)
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- Method for Producing Hydroxymethyl Diphenyloxiranes and Corresponding 1-azolylmethyl-1,2-diphenyloxiranes
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The present invention relates to a method for producing 1-hydroxymethyl-1,2-diphenyloxiranes from 2,3-diphenylpropenals by means of epoxidation and reduction. The formation of objectionable by-products can be suppressed in that the reduction is started be
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Page/Page column 7
(2011/12/13)
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- Substituent effects on the iodine-catalyzed thermal cyclization of 3,4-diphenylbuta-1,3-dienyl isocyanates: Mechanistic studies
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The thermal cyclization of 3,4-diphenylbuta-1,3-dienyl isocyanates 1, generated in situ from the corresponding azides, was investigated using iodine as a catalyst. Diphenylpyridinones 2, phenylnaphthalenes 3, and indenes 4 were produced via intramolecular ring closure. The nature of the substituents on the phenyl rings was found to be crucial to the distribution of cyclized products 2 - 4. The mechanism of the reaction is also discussed.
- Chuang, Ta-Hsien,Chang, Wei-Yu,Li, Chien-Fu,Wen, Yu-Chia,Tsai, Chia-Chen
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p. 9678 - 9686
(2012/01/05)
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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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- Palladium-nanoparticle-catalysed ullmann reactions in ionic liquids with aldehydes as the reductants: Scope and mechanism
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An efficient Ullmann-type reductive homocoupling of aryl, vinyl and heteroaryl halides can be promoted by an aldehyde in tetraalkylammonium ionic liquids under very mild reaction conditions. This simple procedure generates symmetrical biaryls under relatively mild conditions. The ionic liquid is crucial for this process because it behaves simultaneously as a base, ligand and reaction medium. The role of the aldehyde is also discussed and a general mechanism for this unusual reaction is proposed. These results open the way to a new efficient method of Pd-catalysed dehydrogenation of carbonyl compounds.
- Calo, Vincenzo,Nacci, Angelo,Monopoli, Antonio,Cotugno, Pietro
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experimental part
p. 1272 - 1279
(2009/08/14)
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- Development and application of a direct vinyl lithiation of cis-stilbene and a directed vinyl lithiation of an unsymmetrical cis-stilbene
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Equation Presented The vinyl deprotonation of cis-stilbene can be readily achieved using s-BuLi in THF at -25°C. The generated 1-lithio-1,2- diphenylethene undergoes an in situ Z-to-E isomerization, and subsequent reaction with electrophiles results in an efficient stereoselective synthesis of trisubstituted alkenes. A directed vinyl lithiation of the unsymmetrical cis-stilbene 2-styryl-phenyl-carbamic acid tert-butyl ester can be achieved regioselectively, thereby expanding this methodology for further synthetic applications in indole chemistry.
- Cotter, Juliet,Hogan, Anne-Marie L.,O'Shea, Donal F.
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p. 1493 - 1496
(2008/02/02)
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- Palladium(0)-catalyzed Suzuki-Miyaura cross-coupling reactions of potassium aryl- and heteroaryltrifluoroborates with alkenyl bromides
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Efficient palladium(0)-catalyzed Suzuki-Miyaura cross-couplings are described. The reactions involving potassium aryl- and heteroaryltrifluoroborates with alkenyl bromides can generally be carried out using ≤2 mol % of palladium catalyst and 3 equiv of ba
- Molander, Gary A.,Fumagalli, Tiziano
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p. 5743 - 5747
(2007/10/03)
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- Pd-catalysed arylation of propan-1-ol and derivatives: Oxidative role of the arylating agent
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With excess PhI under Pd catalysis, 1-PrOH was converted to a mixture of 3,3-diphenylpropenal and trans-2,3-diphenylpropenal by a concerted, oxidative sequence that involved two arylative couplings and an olefinic aldehyde that was generated in situ.
- Bagnell,Kreher,Strauss
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- Base-catalyzed ring openings of benzocyclobutenones and -ols
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The base-catalyzed ring opening of a number of isomeric E- and Z-benzylidenebenzocyclobutenones and -ols has been studied in both protic and aprotic solvents.Cleavage of the C1-C2 bond results in the formation of stilbenes with mainly, and at times exclusively, retained stereochemistry.For the alcohols, these results point to an oxyanion-induced carbon-carbon bond cleavage leading to a vinyl anion that is protonated with retention of configuration in the protic solvents rather than to an electrocyclic ring opening to an alkoxy o-quinodimethane.Reaction of the Z isomer of benzylidenebenzocyclobutenol with methyllithium in THF at 20 deg C causes isomerization to the E isomer, cleavage of the C1-C2 bond, and recyclization of the resultant isomerized vinyl anion. - Key words: benzylidenebenzocyclobutenones, base-catalyzed ring opening; benzylidenebenzocyclobutenols, base-catalyzed ring opening.
- Bradley, J. C.,Durst, T.
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p. 1660 - 1665
(2007/10/02)
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- Rhodium-katalysierte Hydroformylierung innerer Alkine zu α,β-ungesaettigten Aldehyden
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Keywords: Alkine; Hydroformylierungen; Katalyse; Alkene; Rhodiumverbindungen
- Johnson, John R.,Cuny, Gregory D.,Buchwald, Stephen L.
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p. 1877 - 1879
(2007/10/03)
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- Hypervalent iodine oxidation of allenes: Synthesis of 3-acetoxy-3-alkoxypropynes, 2-alkoxy-3-tosyloxypropanals and phenyl-substituted propenals and propenones
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1-Alkoxyallenes yield 3-acetoxy-3-alkoxypropynes upon oxidation with [(diacetoxy)iodo]benzene at -78°C in dichloromethane. Treatment with [hydroxy(tosyloxy)iodo]benzene under similar conditions gives 2-alkoxy-3-tosyloxypropanals. Phenyl-substituted propen
- Moriarty,Hopkins,Vaid,Vaid,Levy
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p. 847 - 849
(2007/10/02)
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- Addition of 1-(α-Alkoxybenzyl)benzotriazoles to Enol Ethers. New Routes to 1,3-Diethers
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1-(α-Alkoxybenzyl)benzotriazoles undergo reversible ionization in solution to a benzotriazolyl anion (Bt-) and carboxonium cations PhCH:O+R.These cations can attack the β carbon of enol ethers to give cation adducts which add the Bt
- Katritzky, Alan R.,Rachwal, Stanislaw,Rachwal, Bogumila,Steel, Peter J.
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p. 4925 - 4931
(2007/10/02)
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- The Stereochemistry of Organometallic Compounds. XXXIII. Preparation and Reactions of Some Substituted Buta-1,3-dienes
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Hydroformylation and hydrocyanation of 2-methylhex-1-en-3-yne surprisingly both involve addition to the alkyne leading to the formation of formyl- and cyano-buta-1,3-dienes whose reactitvity in Diels-Alder and ene-type reactions has been investigated.
- Campi, Eva M.,Jackson, W. Roy
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p. 471 - 478
(2007/10/02)
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- Carbonylation of Enynes under Hydroformylation Conditions Catalyzed by Rhodium Carbonyl. A New Method for Synthesis of Cyclic Enones
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The reactivities of 1-buten-3-yne derivatives toward hydroformylation were studied using a rhodium catalyst.Unexpectedly, cyclopentenone derivatives were obtained in moderate yields together with formyl-substituted dienes and unsaturated lactones.This rea
- Doyama, Kazuo,Joh, Takashi,Shiohara, Tomoo,Takahashi, Shigetoshi
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p. 4353 - 4360
(2007/10/02)
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- A Two-Step Hydroformylation of Alkynes
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A good-yielding, highly selective hydroformylation protocol for alkynes, involving nickel(0)-catalysed hydrocyanation, previously reported by us, followed by diisobutylaluminum hydride reduction, is presented.
- Campi, Eva,Fitzmaurice, Neil J.,Jackson, W. Roy,Perlmutter, Patrick,Smallridge, Andrew J.
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p. 1032 - 1034
(2007/10/02)
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- HYDROFORMYLATION AND HYDROCARBONYLATION OF ENYMES BY RHODIUM CARBONYL CLUSTER: A NEW ROUTE TO CYCLIC ENONES
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The reaction of but-1-en-3-yne derivates with carbon monoxide and hydrogen in the presence of Rh4(CO)12 catalyst gave formyl-dienes, cyclopentenones and unsaturated lactones, which shows the CC is much more reactive than the C=C moiety and may provide
- Doyama, Kazuo,Joh, Takashi,Takahashi, Shigetoshi
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p. 4497 - 4500
(2007/10/02)
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- REGIOSPECIFIC RING CLEAVAGE OF α,β-EPOXYSILANES TO FORM TRANSITION METAL ENOLATE INTERMEDIATES
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Molybdenum(II) acetate dimer or titanium(IV) i-propoxide induced regiospecific ring cleavage of α,β-epoxysilanes to form the enolate intermediates, which reacted with aldehydes to give the corresponding α,β-unsaturated carbonyl compounds.
- Hirao, Toshikazu,Fujihara, Yoshimi,Tsuno, Shingo,Ohshiro, Yoshiki,Agawa, Toshio
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p. 367 - 368
(2007/10/02)
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