Study on the Conversion of 1,5,3,7-Dichalcogenadiazocines to Cyclic Polychalcogenides

目前的兴趣主要集中在由环状硫醇缩醛裂解产生的含硫原子的活性物种上。特别是，人们预计构象柔性的八元氨基醇遗传缩醛的氧化将引起跨环CH-CH相互作用，得到1，5，3，7-dichalcogenadiazabicyclo[3.3.0]octane-type二卤代化合物，该化合物将通过亲核分子对化合物的亚甲基碳的攻击而发生进一步的碎裂，得到新的环状二卤代化合物。在这项研究中，我们用不同的氧化剂研究了3，7-二取代2H，6H-tetrahydro-1，5，3，7-dischalcogenadiazocines 1到1，2，4-二氯根唑烷2的一种新的环收缩反应。在-78℃条件下，用氧化剂处理二硒二氮杂环化合物和二硫杂环二氮杂环己烷，得到了相应的4H-二氢-1，2，4-二氯氮杂环丙烷和1，2，4-二氯氮杂环丙烷。另一方面，1，5，3，7-二硫杂环氮杂环丙烷与溴在-78℃反应得到了意想不到的6H-二氢-1，2，3，4，7-五氢二氮杂环得到了4-二噻唑烷类化合物。用Br2/S 8或S 2Cl2处理6H-二氢-1，2，3，4，5，7-五硫杂偶氮杂环己烷的产率显著提高。推测2(Se，Te)是由1经催化氧化缩环而成。化合物3由类似方法生成的1，2，4-二噻唑烷2(S)与单质硫依次反应生成。

Current interest has been concentrated on the chalcogen atom-containing reactive species generated by the fragmentation of cyclic chalcogenoacetals. Especially, it was expected that oxidation of conformationally flexible eight membered aminochalcogenoacetals would cause transannular Ch-Ch interaction to give 1,5,3,7-dichalcogenadiazabicyclo[3.3.0]octane-type dichalcogena dications which would undergo further fragmentation to give novel cyclic dichalcogenides by the attack of nuclephiles toward the methylene carbons of the dications. In this study, we carried out the investigation of a novel ring contraction of 3,7-Disubstituted 2H,6H-tetrahydro-1,5,3,7-dischalcogenadiazocines 1 to 1,2,4-dichalcogenazolidines 2 by treating with various oxidizing agents.Treatment of diselenadiazocines and diteluradiazocines with oxidizing agents such as NBS, mCPBA, t-BuOOH, or CuCl_2 afforded the corresponding 4H-dihydro-1,2,4-dichalcogenazolidines in goodyields.On the other hand, treatment of a CH_2Cl_2 solution of 1,5,3,7-dithiadiazocines with bromine at -78 ℃ afforded unexpected 6H-dihydro-1,2,3,4,5,7-pentathlazocines 3 in low yields along with insoluble products and no 1,2,4-dithiazolidines were obtained. Yields of 6H-dihydro-1,2,3,4,5,7-pentathiazocines were dramatically improved by treating 1,5,3,7-dithiadiazocines with Br_2/S_8 or S_2Cl_2.It was assumed that 2(Se, Te) were formed from 1 through oxidative ring contraction via dication. Compound 3 would be formed by the sequent reaction of 1,2,4-dithiazolidines 2(S), which were generated by a similar manner, with elemental sulfur.