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
The [4 + 2] cycloaddition of cyclopentadiene to the (2R)-bornane-10,2-sultam derivative (-)-1b of fumaric monomethyl ester proceeds with high endo and pi-facial diastereoselectivity in the presence of 0.5 mol-equiv. of TiCl4. The major diastereoisomer endo-(2R,3R)-2b, isolated in 87% yield by crystallization, was subjected to X-ray crystal-structure analysis. Steric influence of ethyl- and benzyl-ester analogues (-)-1c and (-)-1d, respectively, is also reported.