Ring enlargement through acyloin condensation of cycloalkane-1,2-dicarboxylic esters

Abstract

Cycloalkane-1,2-dicarboxylic esters of 11-, 12-, and 13-membered rings were prepared from cyclododecanone. Acyloin condensation of these esters in the presence of trimethylchlorosilane followed by acidic hydrolysis afforded 13-, 14-, and 15-membered cycloalkane-1,2-diones in 71–74% yields. The diketones were reduced by treatment with triethyl phosphite and alkali hydroxide into corresponding acyloins.