Stereospecific interconversion of cis- and trans-γ,δ-epoxy α,β-unsaturated ester systems
摘要:
The unprecedented, stereospecific interconversion of cis- and trans-gamma,delta-epoxy alpha,beta-unsaturated ester systems has been realized, which involves the palladium-catalyzed stereospecific alkoxy or hydroxy substitution reaction with double inversion of configuration at the gamma-position as the key step. The new methodology is not only applicable to various disubstituted and trisubstituted epoxy unsaturated esters, but also these interconversions proceed with an extremely high degree of stereoselectivity and efficiency. (C) 2008 Elsevier Ltd. All rights reserved.
Palladium-catalyzed stereospecific epoxide-opening reaction of γ,δ-epoxy-α,β-unsaturated esters with an alkylboronic acid leading to γ,δ-vicinal diols with double inversion of the configuration
A palladium-catalyzed stereospecific epoxide-opening reaction of gamma,delta-epoxy-alpha,beta-unsaturated esters with an alkylboronic acid leading to gamma,delta-vicinal diols is described, which proceeds with retention of the configuration, i.e., via two consecutive S(N)2 processes, to afford the corresponding gamma,delta-cyclic boronates in high yields.