- Stereoselective coupling reaction of (2Z)-β-arylselenocinnamic esters with Grignard reagents in presence of CuI
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Stereoselective synthesis of trisubstituted alkenes linked with ester groups via coupling reaction of (2Z)-β-arylselenocinnamic esters with Grignard reagents in presence of Equal molar quantities of CuI was reported.
- Huang, Xian,Zhao, Chang-Qiu
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- Highly Selective and Catalytic Generation of Acyclic Quaternary Carbon Stereocenters via Functionalization of 1,3-Dienes with CO2
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The catalytic asymmetric functionalization of readily available 1,3-dienes is highly important, but current examples are mostly limited to the construction of tertiary chiral centers. The asymmetric generation of acyclic products containing all-carbon quaternary stereocenters from substituted 1,3-dienes represents a more challenging, but highly desirable, synthetic process for which there are very few examples. Herein, we report the highly selective copper-catalyzed generation of chiral all-carbon acyclic quaternary stereocenters via functionalization of 1,3-dienes with CO2. A variety of readily available 1,1-disubstituted 1,3-dienes, as well as a 1,3,5-triene, undergo reductive hydroxymethylation with high chemo-, regio-, E/Z-, and enantioselectivities. The reported method features good functional group tolerance, is readily scaled up to at least 5 mmol of starting diene, and generates chiral products that are useful building blocks for further derivatization. Systemic mechanistic investigations using density functional theory calculations were performed and provided the first theoretical investigation for an asymmetric transformation involving CO2. These computational results indicate that the 1,2-hydrocupration of 1,3-diene proceeds with high π-facial selectivity to generate an (S)-allylcopper intermediate, which further induces the chirality of the quaternary carbon center in the final product. The 1,4-addition of an internal allylcopper complex, which differs from previous reports involving terminal allylmetallic intermediates, to CO2 kinetically determines the E/Z- and regioselectivity. The rapid reduction of a copper carboxylate intermediate to the corresponding silyl-ether in the presence of Me(MeO)2SiH provides the exergonic impetus and leads to chemoselective hydroxymethylation rather than carboxylation. These results provide new insights for guiding further development of asymmetric C-C bond formations with CO2
- Chen, Xiao-Wang,Zhu, Lei,Gui, Yong-Yuan,Jing, Ke,Jiang, Yuan-Xu,Bo, Zhi-Yu,Lan, Yu,Li, Jing,Yu, Da-Gang
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p. 18825 - 18835
(2019/11/28)
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- Copper(i)-catalysed asymmetric allylic reductions with hydrosilanes
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A copper(i)-catalysed asymmetric allylic reduction enables a regio- and stereoselective transfer of a hydride nucleophile in an SN2′-fashion onto allylic bromides. This transformation represents a conceptually orthogonal approach to allylic substitution reactions with carbon nucleophiles. A copper(i) complex based upon a chiral N-heterocyclic carbene (NHC) ligand allows for stereoselectivity reaching 99% ee. The catalyst enables a stereoconvergent reaction irrespective of the double bond configuration of the starting materials.
- Thanh Nguyen,Thiel, Niklas O.,Teichert, Johannes F.
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supporting information
p. 11686 - 11689
(2017/11/03)
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- Palladium-catalyzed arylation of enoates with iodobenzene: Stereoselective synthesis of trisubstituted olefins
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The Heck reaction between E- and Z-enoates and iodobenzene was studied in the presence of Pd(OAc)2. The stereochemistry in resulting adducts was dependent on the enoate geometry (stereospecific reaction). Best yields were obtained from Z-isomer
- De Fernandes, Talita A.,Vaz, Boniek G.,Da Silva, Alcides J.M.,Esteves, Pierre M.,Eberlin, Marcos N.,Costa, Paulo R.R.
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p. 500 - 506
(2013/08/25)
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- Improved catalysts for the iridium-catalyzed asymmetric isomerization of primary allylic alcohols based on charton analysis
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An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air-stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes that were not accessible previously have been obtained with high levels of enantioselectivity, thus validating the initial hypothesis regarding the selected ligand-design elements. A rationale for the high enantioselectivities achieved in most cases is also presented. Achieving enantioselectivity: An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air-stable complexes relies on preliminary mechanistic information and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation (see figure).
- Mantilli, Luca,Gerard, David,Torche, Sonya,Besnard, Celine,Mazet, Clement
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supporting information; experimental part
p. 12736 - 12745
(2011/02/21)
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- Stereoselective synthesis of 3-alkylcinnamic esters via coupling reaction of (2Z)-3-(aryltelluro) cinnamic esters in presence of CuI
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Coupling reaction of (2Z)-3-(aryltelluro) cinnamic esters with Grignard reagents in presence of CuI produced trisubstituted alkenes containing ester groups with retention of configuration.
- Huang, Xian,Zhao, Chang-Qiu
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p. 237 - 241
(2007/10/03)
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- Stereochemistry of the Reactions of CuI Catalyzed Grignard Reagents with Ethyl (E)- and (Z)-β-Chlorocinnamates
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Ethyl (E)- and (Z)-3-chloro-3-phenyl-2-propenoate were prepared and separated.The (Z)-isomer gave β-alkylated ethyl cinnamates in good yield when reacted with alkyl Grignard reagents in the presence of 10percent CuI.The (Z)-isomer reacted with retention o
- Jalander, Lars,Broms, Merete
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p. 173 - 178
(2007/10/02)
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