作者:Hayashi, Tamio、Takahashi, Makoto、Takaya, Yoshiaki、Ogasawara, Masamichi、Durham, Timothy B.、Miller, J.
DOI:10.15227/orgsyn.079.0084
日期:——
A Chiral Chelating Diene as a New Type of Chiral Ligand for Transition Metal Catalysts: Its Preparation and Use for the Rhodium-Catalyzed Asymmetric 1,4-Addition
作者:Tamio Hayashi、Kazuhito Ueyama、Norihito Tokunaga、Kazuhiro Yoshida
DOI:10.1021/ja037367z
日期:2003.9.1
As a new type of chiral ligand, a C2-symmetric norbornadiene derivative (1R,4R)-2,5-dibenzylbicyclo[2.2.1]hepta-2,5-diene (1) was prepared and used for the rhodium-catalyzed asymmetric addition of organoboron and -tin reagents to alpha,beta-unsaturated ketones, which gave high yields of the 1,4-addition products with up to 99% enantioselectivity.
Rhodium-catalyzed asymmetric 1,4-addition of arylboron reagents to α,β-unsaturated esters
Reaction of arylboronreagents, arylboronic acids or arylborates, which are readily accessible by lithiation of aryl bromides followed by treatment with trimethoxyborane, with α,β-unsaturated esters in the presence of rhodium/(S)-binap catalyst proceeded with high enantioselectivity to give high yields of optically active β-aryl esters of up to 98% ee. The enantioselectivity depends on the steric bulkiness
A highlyenantioselective 1,4-addition of aryltrialkoxysilanes to α,β-unsaturated esters and amides was successfully catalyzed by a chiral rhodiumcomplex generated from [Rh(cod)(MeCN)2]BF4 and (S)-BINAP.