Synthesis and cyclizations of N-(2,3-, 3,4- and 3,5-dimethylphenyl)-beta-alanines.

A series of 1-aryl substituted dihydro-, 5-methyl-dihydro- and 6-methyl-dihydro-2,4(1H,3H)pyrimidinediones and their 2-thio analogues were obtained by reaction of the corresponding beta-alanines or alpha-methyl- and beta-methyl-beta-alanines with urea or potassium thiocyanate. The reaction of N-(2,3- and 3,5-dimethylphenyl)-alpha-methyl-beta-alanines with ethyl acetoacetate gave 1-(2,3- or 3,5-dimethylphenyl)-2,5-dimethyl-1,4,5,6-tetrahydro-4(1H)pyridones. The combined spectral data obtained by (1)H-, (13)C-,(1)H/(13)C (HETCOR) NMR and IR provided useful information about the structure of the products synthesized in this work.