Process for the preparation of 3-alkyl-cyclopentane-1,2-diones, and intermediates therefor

Abstract From the Canadian patent

The disclosure relates to a novel process for the preparation of 3-alkyl-cyclopentane-1,2-diones and, in particular to a novel process for, the preparation of 3-methyl-cyclopentane-1,2-dione also known as Maple lactone. The process comprises condensation of esters of glutaric acid and oxalic acid in a polar aprotic solvent in the presence of an alkali metal alkoxide to form 3,5-dicarboalkoxy-cyclopentane-1,2-dione dialkali metal salts, alkylating said salts with an alkylating agent to form a 2-alkoxy- 3,5-dicarboalkoxy-5-alkyl-cyclopent-2-ene-1-one removing said solvent, therefrom, and hydrolyzing the remainder with a mineral acid to form a 3-alkyl-cyclopentane-1,2-dione.