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2-(3-acylthioureido)benzonitriles. 1. Synthesis and cyclization reactions of 2-(3-acylthioureido)benzonitriles

P. Pazdera, V. Potůček, E. Nováček, I. Kalviňš, P. Trapencieris, and O. Pugovics

Department of Organic Chemistry, Faculty of Natural Sciences, Masaryk University, CS-61137 Brno

Abstract: 2-(3-Acylthioureido)benzonitriles prepared by the addition of 2-aminobenzonitrile to acylisothiocyanates in acetone solution underwent the cyclization reaction either in concentrated sulfuric acid at room temperature forming 2-acylamino-4-imino-4H-benzo[d]-[1,3]-thiazines or under base catalysis with aqueous solution of sodium hydroxide, ammonia or sodium carbonate at room temperature forming 4-amino-1,2-dihydroquinazoline-2-thione. This was also prepared by the rearrangement of 2-acylamino-4-imino-4H-benzo[d]-[1,3]-thiazines in aqueous solution of sodium hydroxide. Under the same conditions ethyl 2-(3-acylthioureido)benzoates reacted to 2-acylamino-4H-benzo[d]-[1,3]-thiazin-4-ones and to known 2-thioxo-1,2,3,4-tetrahydroquinazolin-4-one. This compound is also a product of acid-catalyzed rearrangement of 2-acylamino-4-imino-4H-benzo-[d]-[1,3]-thiazin-4-ones and 2-acylamino-4H-benzo[d]-[1,3]-thiazin-4-ones rearrangement under acid or base catalysis, respectively.

Full paper in Portable Document Format: 454a527.pdf

Chemical Papers 45 (4) 527–540 (1991)