ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Regioselectivity in the 1,3-Dipolar Cycloaddition of Nitrile Oxides to 1-Substituted 3,3-Methylene-5,5-dimethyl-2-pyrrolidinones

L. Jarošková, Ľ. Fišera, J. Maláková, N. Prónayová, and P. Ertl

Department of Organic Chemistry, Faculty of Chemical Technology, Slovak Technical University, SK-812 37 Bratislava

Abstract: The cycloaddition of aryl- and aroylnitrile oxides to l-R-substituted 3,3-methylene-5,5-dimethyl-2-pyrrolidinones (where R is H, n-butyl-, 1,1-dimethylethoxycarbonyl-, 1-methylethenyl-, and acetyl-) proceeds regioselectively under the formation of spiroisoxazolines, namely 7-R-substituted 6-oxo-8,8-dimethyl-1-oxa-2,7-diazaspiro[4,4]non-2-enes. Semiempirical quantum-mechanical methods AM1 were used to rationalize this exclusive regioselectivity. The regiochemistry of the cycloaddition seems to be controlled by the steric effect of the methyl groups at the ring junction.

Full paper in Portable Document Format: 486a404.pdf

Chemical Papers 48 (6) 404–409 (1994)