Alkyl 2-Methyldithiocarbazates in Heterocyclic Synthesis: Preparation of 2-Alkylthio-1,3,4-thiadiazolium Cations and 2-Thioxo-2,3-dihydro-1,3,4-Oxadiazole Derivatives
作者:P. Molina、A. Tárraga、A. Espinosa
DOI:10.1055/s-1988-27672
日期:——
Alkyl 3-acyl-2-methyldithiocarbazates 2, available from alkyl 2-methyldithiocarbazates and acyl chlorides, undergo ring closure by the action of perchloric acid/acetic anhydride to give 2-alkylthio 3-methyl-1,3,4-thiadiazolium salts 4. Compounds 2 also undergo base-catalyzed cyclization to give 4-methyl-2-thioxo-2,3-dihydro-1,3,4-oxadiazoles 3, which react with trimethyloxonium tetrafluoroborate to give 3-methyl-2-methylthio-1,3, 4-oxadiazolium cations 5. 1-Aroyl-2-ethoxyoxalyl-1-phenylhydrazines 6 undergo cyclization by action of trifluoromethanesulfonic acid/acetic anhydride to yield 2-aryl-5-ethoxycarbonyl-3-phenyl-1,3,4-oxadiazolium salts 7.
烷基 3-酰基-2-甲基二硫代卡巴肼 2 可由烷基 2-甲基二硫代卡巴肼和酰基氯化物制得,在高氯酸/乙酸酐的作用下发生闭环反应,生成 2-烷硫基 3-甲基-1,3,4-噻二唑鎓盐 4。化合物 2 还会在碱催化下发生环化反应,生成 4-甲基-2-硫酮-2,3-二氢-1,3,4-恶二唑 3,再与四氟硼酸三甲基锍反应,生成 3-甲基-2-甲硫基-1,3,4-恶二唑阳离子 5。1-Aroyl-2-ethoxyoxalyl-1-phenylhydrazines 6 在三氟甲磺酸/乙酸酐的作用下发生环化反应,生成 2-芳基-5-乙氧羰基-3-苯基-1,3,4-恶二唑鎓盐 7。