Steric factors direct Baylis-Hillman and aldol reactions in titanium tetrachloride mediated coupling between α-keto esters and cyclohex-2-enone derivatives

Abstract

The titanium tetrachloride mediated reaction of α-keto esters with 5,5-dimethylcyclohex-2-enone provides the corresponding Baylis-Hillman adducts exclusively whereas a similar reaction of α-keto esters with cyclohex-2-enone furnishes the corresponding aldol adducts (with high syn-diasteroe-selectivity) as the major product (along with the Baylis-Hillman adducts as the minor product), thus clearly demonstrating the role of the steric factors in directing the reaction pathway.