Ninhydrin reacts with amides in ethanol to produce N- (2-hydroxy-1,3-dioxoindan-2-yl)amide derivatives in nearly quantitative yields. Reaction between these adducts and electron-deficient acetylenic esters in the presence of triphenylphosphine leads to dialkyl 8a-acetylamino-8-oxo-8,8a-dihydro-2H-1-oxacyclopenta[α]indene-2,3-dicarboxylate derivatives in good yields.