Cycloaddition of methyl 2-(2,6-dichorophenyl)-2H-azirine-3-carboxylate to electron-rich 2-azadienes

Abstract

tert-Butyldimethylsililoxy-2-aza-1,3-butadienes react with 2H-azirine 3 leading to Diels–Alder cycloadducts in moderate yields. The reactions are endo- and regioselective with the azirine being added by its less hindered face. There is only one product in the case of 1b, 4b. There are two isomers (4 and 5) from 1a, 1c and 1d. A different result was obtained with the diene 1e. Diene 1e formed products 4e and 8. Some of compounds 4 and 5 have been hydrolysed leading to functionalised aziridines 7. Compound 8 gave aziridine 9.