[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).