Direct Regioselective Dehydrogenation of α‐Substituted Cyclic Ketones

Abstract

AbstractWe disclose a highly regioselective, catalytic one‐step dehydrogenation of α‐substituted cyclic ketones in the presence of 2,3‐dichlorobenzo‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). The high regioselectivity originates from a phosphoric acid‐catalyzed enolization, selectively affording the thermodynamically preferred enol, followed by the subsequent oxidation event. Our method provides reliable access to several α‐aryl and α‐alkyl substituted α,β‐unsaturated ketones.