Synthesis of Cyclic α-Diones, a Class of Natural Flavor Compounds

Abstract

A practical and generally applicable synthesis of the important flavor ingredients corylone (5) and its alkyl homologues 11, 13, 15, and 16 is described, based on alkylation of methyl 4-methoxyacetoacetate (6) with an α-chloro-ketone and subsequent cyclization, hydrolysis, and decarboxylation. The one-pot transformation of methyl 4-chloroacetoacetate to 17 through four consecutive steps is demonstrated. The principle has also been used to prepare the six-membered ring analogues 23 and 24.