DIRECT INTRODUCTION OF HETEROCYCLIC RESIDUES INTO 1,2,4-TRIAZIN-5(2H)ONES

3-Aryl-1,2,4-triazin-5(2H)-ones la-e react with indoles 2a-c in triflu oroacetic acid/chloroform or in boiling butanol or acetic acid to give 6-(indolyl-3)-1,6-dihydro-1,2,4-triazin-5(2H)-ones 3a-g. Oxidation of the dihydro-1,2,4-triazin-5(2H)-ones 3a-e afforded 6-(indolyl-3)-1,2, 4-triazin-5(2H)-ones 4a-e, products of nucleophilic substitution of hy drogen in la-e Refluxing Ib with N-methylpyrrole 5b in butanol for an extended time resulted in the formation of yl)-6-(1-methylpyrrolyl-2)- 1,2,4-triazin-5(2H)-one 4h. The reaction of lac with indoles 2a-c, pyr roles 5a,b, 1,3-dimethyl-2-phenylpyrazol-4-one (8) and aminothiazoles 9a,b in acetic anhydride affords the ryl-6-hetaryl-1,6-dihydro-1,2,4-t riazin-5(2H)-ones 6a-s. Reaction of la-e with N-methylpyrrole 5b in ac etic anhydride gives beside the 1:1 addition products 6h-k also the 2: 1 addition products 7a-c.