Studies on t-BuOK-catalyzed Michael addition of 1,2-allenic ketones with 2-substituted diethyl malonates: highly selective synthesis of β,γ-unsaturated enones

In this paper, we have demonstrated a facile nucleophilic addition of 2-substituted diethyl malonate to various substituted 1,2-allenic ketones to afford β,γ-unsaturated enones using a catalytic amount of t-BuOK as the base. The reaction usually completes within 10 min in acetone at room temperature. The stereoselectivity of the reaction with γ-substituted allenic ketones is very high affording the β,γ-unsaturated E-enones.