Erstes Beispiel einer H‐Verschiebung in ‘Thiocarbonyl‐aminiden’ (N‐(Alkylidensulfonio)aminiden)

Abstract

First Example of an H‐Shift in ‘Thiocarbonyl Aminides’ (N‐(Alkylidenesulfonio)aminides)Reaction of benzyl azide (15a) with the sterically hindered CS group of 4,4‐dimethyl‐1,3‐thiazole‐5(4H)‐thiones 14 (Scheme 3) and 1,1,3,3‐tetramethylindane‐2‐thione (17, Scheme 4) at 80° leads to the corresponding imines in high yield, without formation of any by‐product. In contrast, 15a and 2,2,4,4‐tetramethyl‐3‐thioxocyclobutanone (7) under the same conditions yielded, in addition to imine 19, products 20a and 21 (Scheme 5). For the formation of 20a, a reaction mechanism via [1,4]‐H shift in the intermediate ‘thiocarbonyl aminides’ 23 is proposed (Scheme 6). Product 21 as well as the dithiazole derivative 22, which is formed only in the reaction with 4‐nitrobenzyl azide (15c), are formal adducts of the dipole 23. Whereas precedents are known for the formation of cycloadducts of type 22, the pathway to 21 is not known. Two possible mechanisms of its formation are proposed in Schemes 8 and 9.