Reinvestigation of base-induced skeletal conversion via a spirocyclic intermediate of dibenzodithiocinium derivatives and a computational study using the HF/6-31G* basis set
作者:Keiji Okada、Masato Tanaka
DOI:10.1039/b205588k
日期:2002.11.26
6-methyl-12-oxo-5H,7H-dibenzo[b,g][1,5]dithiocinium salt (1a) with methanolic KOH afforded a mixture of dibenzothiepin derivative 5 in 66% yield. The rearrangement was explained in terms of usual [2,3]-sigmatropic shift via a spirocyclic intermediate. However, an unique rearrangement via an alternative spirocyclic intermediate was observed in 6-methyl-5H,7H-dibenzo[b,g][1,5]dithiocinium salt (2) to give
甲醇处理6-甲基-12-氧代-5 H,7 H-二苯并[ b,g ] [1,5]二硫基cin鎓盐(1a)酸值以66%的收率得到二苯并噻吩衍生物5的混合物。通过经由螺环中间体的通常的[2,3]-σ位移解释了重排。然而,在6-甲基-5 H,7 H-二苯并[ b,g ] [1,5]二硫基cin鎓盐(2)中观察到通过替代的螺环中间体发生的独特重排,从而以29%的收率得到了出乎意料的二苯并噻吩衍生物6在相同的反应条件下,以5%的收率与少量的开环产物7一起使用。为了阐明起源之间的不同行为亚砜导数1a和硫化物在重排的衍生物2中,6-甲基-12-氧代-7,12-二氢-5 H-二苯并[ c,f ]硫[盐(3)作为具有吸电子基团的参考化合物(羰基)制备,并在相同条件下进行处理,以提供酸8和酯 9。据认为,这些产物是由螺环中间体的开环产生的,类似于亚砜导数1a。另一方面,刚性体系10b-苯基-10b,11-二氢-6