[3+2] Cycloaddition of Dimethyl Acetylenedicarboxylate, Methyl Acrylate, and Ethyl Acrylate to 4,5-Dihydro-5-methyl-3H-spiro[benz-2-azepine-3,1'-cyclohexane] N-Oxide

The cycloaddition of methyl acrylate and ethyl acrylate to 4,5-dihydro-5-methyl-3H-spiro[benz-2-azepine-3,1'-cyclohexane] N-oxide proceeds without either regiospecificity or stereospecificity. Eight geometrical isomers of spiro[isoxazolidino[3,2-a]benz-2-azepine-5,1'-cyclohexane] were formed, of which several were isolated as pure samples. The cycloaddition of dimethyl acetylenedicarboxylate proceeds stereoselectively, leading to spiro[isoxazolino[3,2-a]benz-2-azepine-5,1'-cyclohexane] with cis arrangement of the protons at C₍₇₎ and C_(11b).