Stereochemical Studies. XLVI. Studies on the Synthesis of 4-Acetoxy-cyclopentane-1, 3-dione Derivatives

Abstract

As methods for preparing 4-acetoxy-cyclopentane-1, 3-dione derivatives (1), two synthetic schemes were examined. While the successive catalytic reduction and acetylation of cyclopentane-1, 3, 4-triones (2) according to the reported procedure gave the desired 1, the acid-catalyzed condensation of O-acetyl malic anhydride (3) with isopropenyl acetate (4a) and diethyl ketone enol acetate (4b) gave 2-carboxymethyl-5-methyl-3-oxo-2, 3-dihydrofuran (6a) and its 4-methyl derivative (6b), respectively, as the sole isolable product. The structures of 6a and 6b were elucidated from their chemical and spectroscopic behavior. Plausible formation mechanism for the compounds was also proposed.