1,2,4-Triazine Chemistry. 11. Dihydro-1,2,4-triazines: Structural Studies on Sodium Borohydride Reduction Products from Some 3-Methylthio- and 3-Methoxy-1,2,4-triazines

Article abstract of DOI:10.1021/jo01311a008

Sodium borohydride reduction of 3-(methylthio)-5-phenyl- (1a), 3-methoxy-5-phenyl- (1b), 3-(methylthio)-5,6-dimethyl- (1c), 3-methoxy-5,6-dimethyl- (1d), 3-(methylthio)-5-methyl- (1e), 3-methoxy-5-methyl- (1f), 3-(methylthio)- (1g), and 3-methoxy-1,2,4-triazine (1h) gave the corresponding 2,5-dihydro analogues (2a-h).The structures of 2a-h were established by spectral comparison with the known, corresponding 4,5-dihydro tautomers. 2b and 2c were N2-alkylated to 2-ethyl-3-methoxy-5-phenyl-2,5-dihydro-1,2,4-triazine (3a) and 2,5,6-trimethyl-3-(methylthio)-2,5-dihydro-1,2,4-triazine (3b), respectively.Heating 3a with DMAD gave 2-ethyl-5-phenyl-1,2,4-triazin-3(2H)-one (8).