Abstract
2,2-Dimethyl-3-dimethylamino-2H-azirine (1) reacts with the formyl-cycloalkanones 4-8 in boiling benzene to give the 1:1 adducts 13-17 in 60-99% yield (Table). These adducts are N’-[(2-oxo-cycloalkylidene)methyl] derivatives of 2-amino-N,N-dimethylisobutyramide. The reaction mechanism (Scheme 6) is analogous to the mechanism of the reaction of 1 with carboxylic acids and cyclic enolisable 1,3-diketones [1]. Sulfinic acids and 1 undergo a similar reaction at - 15° to yield 2-sulfinamido-N,N-dimethylisobutyramides (Schemes 4 and 7), while sulfonic acids and the azirine 1 lead to a dimeric salt of type 20, which with sodium hydroxide gives the dihydropyrazine 21 (Scheme 5).
Chandrasekhar, B Parthasarathi