Protonation of tricarbonyldieneiron complexes: Acid-catalysed cyclization of tricarbonylmyrceneiron

Abstract

Treatment of tricarbonylmyrceneiron (1) with catalytic amounts of anhydrous tetrafluoroboric acid results in cyclization to give tricarbonyl(3,3-dimethyl-1-vinylcyclohexene)iron (4). Protonation of (4) with excess anhydrous tetrafluoroboric acid gives a tetracarbonylallyliron complex (5) which can be reduced with sodium borohydride to 1-ethylidene-3,3-dimethylcyclohexane (6).