Abstract The Biginelli reactions of salicylaldehyde and 2-hydroxy-l-naphthaldehyde with ethyl or methyl acetoacetate, ethyl benzoylacetate, and urea have been reinvestigated both in the structures of the reaction products and in the reaction conditions. Salicylaldehyde with ethyl and methyl acetoacetate resulted in oxygen-bridged tricyclic tetrahydro pyrimidines, whereas with ethyl benzoylacetate afforded the only normal 3, 4-dihydropyrimidin-2-one. ...
