Synthesis, structure, and reactivity of a 4-oxo-η3-cyclohexenyl molybdenum complex; diastereofacial selectivity in the reactions of the derived lithium enolate

Abstract

Nucleophilic attack on the 1,3-diene cation formed by reaction of 1-methoxycyclohexa-1,3-diene with [Mo(NCMe)₂(CO)₂(η⁵-C₉H₇)][BF₄] leads to demethylation and formation of the crystallographically identified 4-oxo-η³-cyclohexenyl complex [Mo(η³-C₆H₇O)(CO)₂(η⁵-C₉H₇)], which is attacked by electrophiles on the oxygen of the oxo-η³-allyl, and forms an E-enolate on deprotonation which reacts selectively with Mel, Etl, and PhCHO on the opposite face of the C₆ ring to which the molybdenum is co-ordinated.