Stereospecific nucleophilic addition reactions to olefins. Addition of thiols to .alpha.,.beta.-unsaturated carboxylic acid derivatives
摘要:
Stereospecific nucleophilic addition of thiols to derivatives of alpha,beta-unsaturated carboxylic acids is described. The additions are carried out at room temperature in the presence of a catalytic amount of lithium thiolate and an excess of thiol as a proton source. Erythro and threo adducts are obtained with high diasteroselectivity from E and Z olefins, respectively. This anti addition suggests that the enolate generated by nucleophilic addition undergoes rapid protonation prior to conformational change in the intermediate.
Stereospecific nucleophilic addition of thiols to derivatives of alpha,beta-unsaturated carboxylic acids is described. The additions are carried out at room temperature in the presence of a catalytic amount of lithium thiolate and an excess of thiol as a proton source. Erythro and threo adducts are obtained with high diasteroselectivity from E and Z olefins, respectively. This anti addition suggests that the enolate generated by nucleophilic addition undergoes rapid protonation prior to conformational change in the intermediate.