1,3‐Dipolare Cycloadditionen von 2‐(Benzonitrilio)‐2‐propanid mit 4,4‐Dimethyl‐2‐phenyl‐2‐thiazolin‐5‐thion und Schwefelkohlenstoff

1,3‐Dipolar Cycloadditions of 2‐(Benzonitrilio)‐2‐propanide with 4,4‐Dimethyl‐2‐phenyl‐2‐thiazolin‐5‐thione and Carbon Disulfide Irradiation of 2,2‐dimethyl‐3‐phenyl‐2 H ‐azirine ( 11 ) in the presence of 4,4‐dimethyl‐2‐phenyl‐2‐thiazolin‐5‐thione ( 7 ) yields a mixture of the three (1:1)‐ad‐ducts 8 , 12 and 13 ( Schemes 3 and 6 ). The formation of 8 and 12 can be explained by 1,3‐dipolar cycloaddition of 2‐(benzonitrilio)‐2‐propanide ( 1b ) to the C, S‐double bond of 7. Photochemical isomerization of 12 leads to the third isomer 13 ( Schemes 3 and 7 ). Photolysis of the azirine 11 in the presence of carbon disulfide gives a mixture of two (2:l)‐adducts, namely 12 and 13 ( Scheme 4 ). A reaction mechanism via the intermediate formation of the 3‐thiazolin‐5‐thione b is postulated. The structure of the heterocyclic spiro compound 13 has been established by single‐crystal X‐ray structure determination ( cf. Fig. 1 and 2 ).