Synthesis of Azlactones, Phenylpyruvic Acid and 1,2,4-Triazine Derivatives Under Microwave Irradiation

Microwave (MW) irradiation has been used in each step for the transformation of acyl glycines 2 to 6-benzyl-3-thioxo-2,3,4,5-tetrahydro-1,2,4-triazin-5-one (7a), and its 4-phenyl derivatives 7b and 7c. The oxazolone 3a was also transformed to phenylpyruvic acid 5, whose thiosemicarbazone 6 can be cyclized to 7a under MW. Methylation of 7c gave the respective S- and / or N-methylated derivatives, 8 and 9, based on the reaction conditions.