T. Nishio, H. Asai, T. Miyazaki
Jul 5, 2000
Citations
0
Influential Citations
11
Citations
Journal
Helvetica Chimica Acta
Abstract
The photochemical reactions of 2-substituted N-(2-halogenoalkanoyl) derivatives 1 of anilines and 5 of cyclic amines are described. Under irradiation, 2-bromo-2-methylpropananilides 1a – e undergo exclusively dehydrobromination to give N-aryl-2-methylprop-2-enamides (=methacrylanilides) 3a – e (Scheme 1 and Table 1). On irradiation of N-alkyl- and N-phenyl-substituted 2-bromo-2-methylpropananilides 1f – m, cyclization products, i.e. 1,3-dihydro-2H-indol-2-ones (=oxindoles) 2f – m and 3,4-dihydroquinolin-2(1H)-ones (=dihydrocarbostyrils) 4f – m, are obtained, besides 3f – m. On the other hand, irradiation of N-methyl-substituted 2-chloro-2-phenylacetanilides 1o – q and 2-chloroacetanilide 1r gives oxindoles 2o – r as the sole product, but in low yields (Scheme 3 and Table 2). The photocyclization of the corresponding N-phenyl derivatives 1s – v to oxindoles 2s – v proceeds smoothly. A plausible mechanism for the formation of the photoproducts is proposed (Scheme 4). Irradiation of N-(2-halogenoalkanoyl) derivatives of cyclic amines 5a – c yields the cyclization products, i.e. five-membered lactams 6a, b, and/or dehydrohalogenation products 7a, c and their cyclization products 8a, c, depending on the ring size of the amines (Scheme 5 and Table 3).