Electron-Deficient Olefin Ligands Enable Generation of Quaternary Carbons by Ni-Catalyzed Cross-Coupling
作者:Chung-Yang (Dennis) Huang、Abigail G. Doyle
DOI:10.1021/jacs.5b02503
日期:2015.5.6
A Ni-catalyzed Negishi cross-coupling with 1,1-disubstituted styrenyl aziridines has been developed. This method delivers valuable β-substituted phenethylamines via a challenging reductive elimination that affords a quaternary carbon. A novel electron-deficient olefin ligand, Fro-DO, proved crucial for achieving high rates and chemoselectivity for C-C bond formation over β-H elimination. This ligand
enantioselective Negishi cross‐coupling reaction, and the first arylation of α‐halo esters with arylzinc halides, are disclosed. Employing a cobalt‐bisoxazoline catalyst, various α‐arylalkanoic esters were synthesized in excellent enantioselectivities and yields (up to 97 % ee and 98 % yield). A diverse range of functional groups, including ether, halide, thioether, silyl, amine, ester, acetal, amide, olefin
Enantioselective Synthesis of Axially Chiral Tetrasubstituted Allenes via Lipase-Catalyzed Desymmetrization
作者:Jan Deska、Matthias Hammel
DOI:10.1055/s-0032-1317524
日期:——
transesterification of prochiral tetrasubstituted allenic diols yielding highly enantioenriched axiallychiral allenyl monoesters. In combination with subsequent 5-endo-trig cyclizations geminally disubstituted dihydrofurans are accessible in high optical purity. Lipase from Pseudomonas fluorescens efficiently catalyzes the transesterification of prochiral tetrasubstituted allenic diols yielding highly
Directed Nickel-Catalyzed Negishi Cross Coupling of Alkyl Aziridines
作者:Daniel K. Nielsen、Chung-Yang (Dennis) Huang、Abigail G. Doyle
DOI:10.1021/ja4076716
日期:2013.9.11
Herein we report a nickel-catalyzed C-C bond-forming reaction between simple alkyl aziridines and organozinc reagents. This method represents the first catalytic cross-coupling reaction employing a nonallylic and nonbenzylic Csp(3)-N bond as an electrophile. Key to its success is the use of a new N-protecting group (cinsyl or Cn) bearing an electron-deficient olefin that directs oxidative addition
在这里,我们报告了简单的烷基氮丙啶和有机锌试剂之间的镍催化的 CC 键形成反应。这种方法代表了第一个采用非烯丙基和非苄基 Csp(3)-N 键作为亲电子试剂的催化交叉偶联反应。其成功的关键是使用带有缺电子烯烃的新 N 保护基团(cinsyl 或 Cn),该烯烃可指导氧化加成并促进还原消除。还介绍了与阐明交叉耦合机制有关的研究。
Synthesis and Structural Analysis of Oligo(naphthalene-2,3-diyl)s
作者:Takahisa Motomura、Hideko Nakamura、Michinori Suginome、Masahiro Murakami、Yoshihiko Ito
DOI:10.1246/bcsj.78.142
日期:2005.1
Oligo(naphthalene-2,3-diyl)s are synthesized by the palladium-catalyzed cross-coupling reactions of 2-naphthylzinc compounds with 2-bromonaphthalene derivatives. An NMR analysis together with an X-ray diffraction study supports the conjecture that the helical secondary structure is a common feature of the assemblies in which naphthalene-like aromatic units are linked together between the β-positions in series.