Synthesis and Cyclizations of N-(2,3-, 3,4- and 3,5-Dimethylphenyl)-β-alanines

A series of 1-aryl substituted dihydro-, 5-methyldihydro- and 6-methyl-dihydro-2,4(1H,3H)pyrimidinediones and their 2-thio analogues were obtained by reaction of the corresponding β-alanines or α-methyl- and β-methyl-β-alanines with urea or potassium thiocyanate. The reaction of N-(2,3- and 3,5-dimethylphenyl)-α-methyl-β-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.