Generation and cycloaddition reactions of substituted 2-nitro-1,3-dienes

Abstract

4-Acyloxy-2-substituted-3-nitro-1-butenes have been utilized as convenient precursors of the corresponding 2-nitro-3-substituted-1,3-butadienes which could be easily generated in situ by heating or by treatment with sodium acetate and trapped by suitable partners such as methyl acrylate, cyclopentadiene or ethyl vinyl ether. The expected cycloadducts are regiochemically formed by reaction with methyl acrylate, while the initially formed adducts with cyclopentadiene underwent thermal Cope or hetero-Cope rearrangements leading to the formation of nitro-substituted bicyclic compounds. The thermal rearrangement of the oxazine-N-oxides resulting through hetero Diels-Alder reaction with ethyl vinyl ether as cycloaddition partner led to the formation of 1,2-oxazole-3-propionaldehydes. The wide variety of highly functionalized carbocyclic and heterocyclic compounds generated through the use of these multi-coupling reagents provided useful synthons for the construction of simple and complex natural compounds.