Enantioselective 1,4-additions of ClMeAl(CHCHR) (R = alkyl, alkenyl, Ph) to cyclohexenones
作者:D. Willcox、S. Woodward、A. Alexakis
DOI:10.1039/c3cc48191c
日期:——
Chloromethylvinyl alanes (E)-ClMeAl(CH=CHR) prepared directly from terminal alkynes undergo 1,4-addition to cyclohexenone and 3-methylcyclohexenone in moderate to good yield (30-70%) and good to excellent stereoselectivity (80-98% ee) using readily available copper(I) sources and chiral ligands.
Asymmetric 1,4-addition of alkenylzirconium reagents to α,β-unsaturated ketones catalyzed by chiral rhodium complexes
作者:Shuichi Oi、Takashi Sato、Yoshio Inoue
DOI:10.1016/j.tetlet.2004.04.171
日期:2004.6
Highly enantioselective 1,4-addition of alkenylzirconocene chlorides to alpha-enones Was found to be catalyzed by a chiral rhodium complex generated from [Rh(cod)(MeCN)(2)]BF4 and (S)-BINAP. The reaction can be applied to either cyclic or acyclic enones and the optical yield was LIP to 99% ee. The reaction mechanism would involve the transmetalation between the alkenylzirconocene chloride and the rhodium complex to give the alkenylrhodium species as a key intermediate. (C) 2004 Elsevier Ltd. All rights reserved.
Chiral dihydrobenzofuran-based diphosphine (BICMAP): optical resolution and application to rhodium(I)-catalyzed asymmetric 1,4-addition of aryl- and alkenylboronic acids to cyclic enones
Chiral dihydrobenzofuran-based diphosphine ligand (BICMAP) 1 was used as a ligand for the rhodium(I)-catalyzed asymmetric1,4-addition of arylboronicacids to cyclic enones up to 99% ee. We also found that the BICMAP-rhodium system was an efficient catalyst for the 1,4-addition of alkenylboronic acids to 2-cyclohexenone in good enantioselectivities.