Ring Opening of 2,5-Didehydrothiophene: Matrix Photochemistry of C<sub>4</sub>H<sub>2</sub>S Isomers
作者:Yong Seol Kim、Hiroshi Inui、Robert J. McMahon
DOI:10.1021/jo061678l
日期:2006.12.1
energy surface. The photochemical formation of thioketene 6 from either diyl 4 or sulfide 3 may be interpreted in line with a recent computational prediction on the thermal ring opening of diyl 4, which favors C−S bond cleavage, leading to 6, over C−C bond cleavage, leading to 3. Photolysis of matrix-isolated 3,4-thiophenedicarboxylic acid anhydride (11) enables the observation of the photoequilibration
基质分离的2,5-二碘噻吩(10)的辐照(λ> 254 nm)产生分配给乙炔基硫代乙烯酮(6)的IR谱带。二乙炔硫醚(3),这将形成初期2,5- didehydrothiophene(的复古伯格曼环化反应的过程4)时,没有检测到。在相同的照射条件下,基质分离的二乙炔基硫醚(3)重排为硫代乙烯酮6和丁三烯硫酮(5),这是C 4 H 2 S势能表面上的全局最小值。由二基4或硫化物3形成硫代烯酮6的光化学形成可以根据对二基4的热开环的最新计算预测来解释,这相对于C-C键断裂(导致3)更有利于C-S键断裂(导致6)。基质分离的3,4-噻吩二羧酸酐(11)的光解使得能够观察到三种低能C 4 H 2 S异构体,丁三烯硫酮(5),乙炔基硫代乙烯酮(6)和丁二炔基硫醇(7)的光平衡。明显的[1,3]-氢转移。