N-Methylhydrazinecarbothioamide → 5-ethyl-4-methyl-4H-1,2,4-triazole-3-thiol

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Reaction Steps

Introduction of the 4-methyl-2,4-dihydro-[1,2,4]triazol-3-one moiety is accomplished by O-alkylation of A-5 with 3-iodomethyl-5-methanesulfonyl-4-methyl-4H-[1,2,4]triazole which is prepared as depicted in SCHEME B. Condensation of ethyl hydroxy acetate and 4-methyl-3-thiosemicarbazide afforded 5-ethyl-4-methyl-2,4-dihydro-[1,2,4]triazole-3-thione (B-3) which is S-alkylated (step 2), converted to the chloromethyl compound (step 3), oxidized to the sulfone (step 4) and converted to the desired iodomethyl compound B-5b via a Finkelstein reaction (step 5).

Provenance & Evidence