ADAMANTANE DERIVATIVES .4. UNEXPECTED DEBENZYLATION OF RING-CLOSURE OF 1-(1-ADAMANTYLCARBONYL)-4-BENZYLTHIOSEMICARBAZIDE WITH SULFURIC-ACID

Cyclization of 1-(1-adamantylcarbonyl)-4-substituted thiosemicarbazide s 2a-e with sulphuric acid at ambient temperature or by heating with p hosphorus oxychloride yielded the corresponding 2-(1-adamantyl)-5-amin o-1,3,4-thiadiazoles 3a-e. Cyclization of 1-(1-adamantylcarbonyl)-4-be nzylthiosemicarbazide 2f with sulphuric acid gave the debenzylated pro duct 2-(1-adamantyl)-5-amino-1,3,4-thiadiazole 4. On the other hand, c yclization of 2f using phosphorus oxychloride yielded 2-(1-adamantyl)- 5-benzylamino-1,3,4-thiadiazole 3f.