Intramolecular cyclization of gem-benzylaminoallylcyclohexane under the action of sulfuric acid

When treated with 85% sulfuric acid at 85°C, gem-benzylaminoallylcyclohexane is converted to spiro[tetrahydrobenz-2-azepine-3-cyclohexane], while at 20°C or in boiling chloroform 3,4,5,6-tetrahydro-3-benzyl-6-methylspiro[1,2,3-oxathiazine-2,2-dioxide-4- cyclohexane] is formed as the major product. The second compound is cleaved by alcohol solution of alkali to 1-benzyl-4-methylspiro[azetidine-2-cyclohexane]. ©1999 KluwerAcademic/Plenum.