Photoinduced molecular rearrangements. The photochemistry of 1,2,4-oxadiazoles in the presence of sulphur nucleophiles. Synthesis of 1,2,4-thiadiazoles
作者:Nicolò Vivona、Silvestre Buscemi、Stefano Asta、Tullio Caronna
DOI:10.1016/s0040-4020(97)00784-9
日期:1997.9
The photochemistry of some 1,2,4-oxadiazoles in the presence of sulphur nucleophiles has been investigated. Irradiation of the 5-amino-3-phenyl- and 3,5-diphenyl-1,2,4-oxadiazole at γ = 254 nm in methanol in the presence of sodium hydrogen sulphide or thiols gave a photo-induced redox reaction at the ring ON bond, leading to the corresponding N-substituted benzamidines. By contrast, irradiation of
已经研究了在硫亲核试剂存在下一些1,2,4-恶二唑的光化学性质。在存在硫化氢钠或硫醇的情况下,在甲醇中以γ = 254 nm辐照5-氨基-3-苯基-和3,5-二苯基-1,2,4-恶二唑,在光催化下进行光诱导的氧化还原反应。环ON键,导致相应的N取代的苯甲s。相反,在硫脲或硫代氨基甲酸酯的存在下辐射5-氨基-3-苯基-1,2,4-恶二唑,基本上得到3-苯基-5-取代的1,2,4-噻二唑,其假定为N环光解物种与硫亲核试剂之间形成S键。继而,在硫代酰胺存在下,相同的5-氨基-3-苯基-1,2,4-恶二唑的辐照再次提供了氧化还原反应。另外,还形成了一定数量的3-苯基-5-取代-1,2,4-噻二唑。报告了一些机械方面的考虑,并强调了导致1,2,4-噻二唑的合成方法。