Stereoselectivity in the reaction of Methylmagnesium bromide (CH3MgBr) and Methyllithium (CH3Li) with a Tricarbonyldieneiron diester complex

Abstract

Tricarbonyl(η4-5α,5β-dimethoxycarbonylcyclohexa-1,3-diene) iron (1) reacted stereoselectively with CH3MgBr to furnish in 65% yield a 2:1 epimeric mixture of -β-endo)- and α-(exo)-(l'- hydroxyisopropyl) complexes, 2 and 3. The reaction of 1 with CH3Li was complex and showed that the ratio of products from the reaction on the β-(endo) and α-(exo) faces was 13:9. An explanation is advanced for metalalkyl reactions of 1 occurring preferentially on the β-(endo) face, whereas alkaline hydrolysis takes place exclusively on the α-(exo) face.