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-2H-azirine (11) in the presence of 4,4- dimethyl-2-phenyl-2-thiazolin-5-thione (7) yields a mixture of the three (1:1)-adducts 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 (2:1)-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).