Organometallics in synthesis: alkylation of tricarbonyldienyliron cationic complexes with organocadmium reagents

Abstract

Alkylations of tricarbonyldienyliron salts with organocadmium reagents have been achieved in high yields. The tricarbonyl-(2-methylcyclohexadienyl)iron cation reacts regioselectively mainly at the unhindered terminus and stereospecifically on the face opposite to the Fe(CO)₃ group. Regioselectivity is poor in the acyclic dienyl series, although the cisoid geometry of the double bond is retained in the product. The reaction of dibut-2-enylcadmium occurs at the 3-position with allylic rearrangement.