Synthesis of five-membered heterocycles containing a nitrogen-oxygen bond via O-acylation of aliphatic nitro compounds.

Abstract

O-Acylation of primary aliphatic nitro compounds with acid chlorides in N, N-dimethylacetamide led to the formation of nitrile oxides, which cyclized in situ with olefinic dipolarophiles in a 1, 3-dipolar cycloaddition mode to afford 2-isoxazoline derivatives. Optimum reaction conditions were investigated, and the use of several types of dipolarophiles, such as acetylenes, Schiff bases, aromatic nitriles, and ketones, in this cycloaddition resulted in the formation of the corresponding cycloadducts, namely isoxazoles, 1, 2, 4-oxadiazolines, 1, 2, 4-oxadiazoles, and 1, 4, 2-dioxazoles, respectively, in reasonable yields.