Studies on isoxazoles. XII. Novel syntheses of 4-isothiazolin-3-thiones and bis(3-isoxazolyl) disulfides from 4-isoxazolin-3-thiones.
作者:SOJI SUGAI、KAZUO TOMITA
DOI:10.1248/cpb.28.487
日期:——
Heating of 2, 5-dimethyl-4-isoxazolin-3-thione (IIa) in acidic media gave 2, 5-dimethyl-4-isothiazolin-3-thione (IIIa) and bis (5-methyl-3-isoxazolyl) disulfide (IVa) in poor yields. On the other hand, 2-methyl-5-phenyl-4-isoxazolin-3-thione (IIe) afforded only bis (5-phenyl-3-isoxazolyl) disulfide (IVb). The reactions of 4-isoxazolin-3-thiones (IIa-d) with hydrogen sulfide or thioacetic acid in 48% hydrobromic acid gave 4-isothiazolin-3-thiones (IIIa-d) in moderate yields, while 5-phenyl-4-isoxazolin-3-thiones (IIe, f) afforded 3-imino-5-phenyl-1, 2-dithiols (VIe, f) in addition to 5-phenyl-4-isothiazolin-3-thiones (IIIe, f). A reaction mechanism is proposed. The thiol (VIe) was treated with base to give IIIe. An improved synthesis of the disulfides (IVa, b) was developed by the reaction of 2-methyl-4-isoxazolin-3-thiones (IIa, b) or 2-benzyl-4-isoxazolin-3-thiones (IIg, h) with bromine.
在酸性介质中加热2,5-二甲基-4-异噁唑啉-3-硫酮(IIa)得到2,5-二甲基-4-异噁唑烯-3-硫酮(IIIa)和双(5-甲基-3-异噁唑基)二硫化物(IVa),产率较低。另一方面,2-甲基-5-苯基-4-异噁唑啉-3-硫酮(IIe)仅得到双(5-苯基-3-异噁唑基)二硫化物(IVb)。4-异噁唑啉-3-硫酮(IIa-d)与硫化氢或噻吩乙酸在48%的溴化氢酸中反应,得到4-异噁唑烯-3-硫酮(IIIa-d),产率适中,而5-苯基-4-异噁唑啉-3-硫酮(IIe, f)则除了得到5-苯基-4-异噁唑烯-3-硫酮(IIIe, f)外,还生成了3-亚氨基-5-苯基-1,2-二硫醇(VIe, f)。提出了一种反应机制。将硫醇(VIe)与碱处理得到IIIe。通过2-甲基-4-异噁唑啉-3-硫酮(IIa, b)或2-苄基-4-异噁唑啉-3-硫酮(IIg, h)与溴反应,发展了一种改进的二硫化物合成方法(IVa, b)。