Dj. Collins et al., Dihydro-1,2,4-triazin-6(1H)-ones. IV - Chemical modification of 3-phenyl-4,5-dihydro-1,2,4-triazin-6(1H)-ones, AUST J CHEM, 53(2), 2000, pp. 137-141
Reaction of 3-phenyl-4,5-dihydro-1,2,4-triazin-6(1H)-one (1) and its 5,5-di
methyl derivative (4) with phosphorus pentasulfide gave the corresponding 6
-thiones (2) and (5); methylation of (2) gave the 6-methylsulfanyl-3-phenyl
-4,5-dihydro-1,2,4-triazine (3), also obtained by reaction of 6-chloro-3-ph
enyl-4,5-dihydro-1,2,4-triazine (8) with sodium thiomethoxide. Reaction of
(8) with morpholine afforded the 6-(morpholin-4'-yl) derivative (9). Reacti
on of (1) with isopropyl isocyanate gave N-isopropyl-6-oxo-3-phenyl-1,4,5,6
-tetrahydro-1,2,4-triazine-1-carboxamide (19a), and a Mannich reaction of (
1) with morpholine and formaldehyde gave the 1-morpholinomethylene derivati
ve (20a). Attempts to effect cycloaddition of 1-methyl-3-phenyl-1,2,4-triaz
in-6(1H)-one (12) with a benzonitrile oxide failed. Reaction of the thione
(2) with 1,3-dipolarophiles gave unstable adducts.