1, 3, 4-THIADIAZOLES. REGIOSELECTIVE O-DEMETHYLATION ON DEHYDRATIVE CYCLIZATION OF 1-(3, 4, 5-TRIMETHOXYBENZOYL) 4-SUBSTITUTED …

M Al-Omar, OA Al-Deeb, HA Al-Khamees…

Index: Al-Omar, Mohamed; Al-Deeb, Omar A.; Al-Khamees, Hamad A.; El-Emam, Ali A. Phosphorus, Sulfur and Silicon and the Related Elements, 2004 , vol. 179, # 12 p. 2509 - 2517

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Citation Number: 14

Abstract

Cyclization of 1-(3, 4, 5-trimethoxybenzoyl)-4-substituted thiosemicarbazides 2a–g with sulphuric acid at ambient temperature afforded the selectively demethylated products 2-(4- hydroxy-3, 5-dimethoxyphenyl)-5-substituted amino-1, 3, 4-thiadiazoles 4a–g. Meanwhile, dehydrative cyclization of 1-(3, 4, 5-trimethoxybenzoyl)-4-(benzyl or t-butyl) thiosemi- carbazides 2h, i with sulphuric acid yielded 2-(4-hydroxy-3, 5-dimetho xyphenyl)-5-amino- ...