Synthesis of 2,3-disubstituted cyclopent-2-en-1-ones from 6-methoxyindanone

Abstract

A new route to 2,3-disubstituted cyclopentenones (4) is described. Reductive alkylation of 6-methoxyindanone (1) in potassium and liquid ammonia followed by addition of lithium bromide and an alkyl halide gives dihydroindanones (2). Ozonolysis of the dihydroindanones results in cleavage of the vinyl ether double bond, and oxidation of the resulting aldehyde (3) leads to the 2,3-disubstituted cyclopentenones (4), after spontaneous decarboxylation of the intermediate β-keto acid.