Synthesis of Novel Dihydro-1, 2, 4-triazoles from Thiosemicarbozones via 1, 4-Diacetyl-3-methylsulfonyl-4, 5-dihydro-1H-1, 2, 4-triazoles as Key Intermediates

抄録

Novel 3, 5-disubstituted 4, 5-dihydro-1H-1, 2, 4-triazoles were synthesized by nucleophilic substitution of 1, 4-diacetyl-3-methylsulfonyl-4, 5-dihydro-1H-1, 2, 4-triazoles (15a-c), which were obtained by oxidation of 1, 4-diacetyl-3-methylthio-4, 5-dihydro-1H-1, 2, 4-triazoles (5a-c) with 2 mol eq of m-chloroperbenzoic acid. Acetylation of aldehyde or ketone S-methylisothiosemicarbazones (3a-c) with acetic anhydride at room temperature gave aldehyde or ketone 4-acetyl-3-methyl-isothiosemicarbazones (4a-c), which cyclized with acetic anhydride under heating to give 5a-c. Compounds 5a-c were also obtained by the reaction of 3a-c with acetic anhydride under heating.