Synthesis of 1-substituted 4-ethoxycarbonyl-5- (ethoxycarbonylmethyl) pyrazoles Diethyl acetone-1, 3-dicarboxylate reacts with N, N-dimethylforma- mide dimethyl acetal (DMFDMA) in ethanol at room temperature. Unexpected product dichotomy is produced in the Biginelli-like condensation of 2-hydroxybenzaldehyde with urea or thiourea and dimethyl or diethyl acetone-1,3-dicarboxylate, respectively, as active methylene components. Ethyl 2-amino-4-(2-ethoxy-2-oxoethyl)thiazole-5-carboxylate (2a), prepared from diethylacetone-1,3-dicarboxylate, sulfuryl chloride and thiourea. Synthesis of diethyl 2,2-diethyl-3,5-dioxopimelate by the reaction of ethyl 3-chloro-3-oxo-2,2-dimethylpropionate with diethyl acetone-1,3-dicarboxylate.
