The curtius rearrangement of Ethyl 1 (2 – azido – 2 oxoethyl) – 6 – methyl – 2 – oxo – 4 – (3 – substituted) 1, 2, 3, 4 – tetrahydropyrimidine -5 – carboxylate prepared from the readily accessible 4 (1 – substituted) – 5 ethoxy carbonyl – 6 methyl] 3, 4 – dihydropyrimidine – 2 (1H) – one was investigated in presence of ethanol, substituted phenols and substituted amines. The resulting carbamate...

The mechansim of the three-component Biginelli dihydropyrimidine synthesis was reinvestigated using (1)H and (13)C NMR spectroscopy. Condensation of benzaldehyde, ethyl acetoacetate, and urea (or N-methylurea) in CD(3)OH according to the procedure described by Biginelli produced the expected 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylates. According to NMR measurements, ther...