Short and tandem syntheses of spiro[2.5]octane-5,7-dione and spiro[3.5]nonane-6,8-dione via diethyl acetonedicarboxylate

A general synthetic route to spiro[2.5]octane-5,7-dione and spiro[3.5]nonane-6,8-dione that involves cyclization of the related acrylates and diethyl acetonedicarboxylate, followed by decarboxylation, has been developed. Compared with previous synthetic methods, the developed protocol avoids the use of column chromatography in each of the synthetic steps. Therefore, it can be readily scaled-up. The use of diethyl acetonedicarboxylate under mild conditions to build the skeleton of 1,3-cyclohexanedione has proved to be very efficient.