reactions of 1,2,3-trisubstituted aziridines 1 with 1,3-thiazole-5(4H)-thiones 6 in toluene yielded, in general, a mixture of two diastereoisomeric spirocyclic [2+3] cycloadducts. The formation of these products can be explained by a stereoselective electrocyclic ring opening of 1 to give an azomethine ylide 2 as the reactive intermediate, which is trapped immediately by 6via a stereoselective 1,3-dipolar
1,2,3-三取代的
氮丙啶1与1,3-
噻唑-5(4 H)-
硫酮6在
甲苯中的热反应通常产生两种非对映异构的螺环[2 + 3]环加合物的混合物。这些产物的形成可以通过将立体选择性的电环开环为1来给出,以得到作为反应性中间体的甲
亚胺基内酯2,其通过立体选择性的1,3-偶极环加成立即被6捕获。仅在的情况下,反式-二甲基-1-(4-
甲氧基苯基)
氮丙啶-2,3-二
羧酸酯(反式- 1A,四个非对映异构cycloadducts形成)(方案4)。该结果是通过所述中间偶氮甲碱内鎓盐的异构化合理化顺-图2a到反式-图2a。