4-Phenyl-1,2-dithiolium perchlorate reacts with ammonia in ethanol to yield 4-phenyl-isothiazole. The reaction is general for dithiolium salts. When unsymmetrical dithiolium salts are treated with ammonia, the major product and, under many conditions, the only product is the 5-substituted isothiazole. Of the four possible mechanisms for these reactions, an addition-elimination mechanism has been shown
[2+2] Cycloaddition Reactions of Isothiazoles Intramolecular Nucleophilic Attack On Isothiazolium Salts Preparation of New β-Lactam Systems Based on Isothiazole Nucleus
作者:Mohamed E. Hassan
DOI:10.1002/bscb.19850940213
日期:——
Abstract[2+2] cycloaddition reactions of isothiazoles with diphenyl ketene afford new fused β‐lactam systems. The intramolecular nucleophilic attack of carbanions on isothiazolium salts is found to take place on the ring sulphur atom. 2‐H‐2‐benzoyl‐1, 3‐thiazines were prepared and allowed to react with diphenyl ketene, or with acid chloride in the presence of a tertiary amine, to afford the corresponding β‐lactams.