Synthesis and reactions of bicyclic isoxazoline derivatives

CHED 321

Rosaura Padilla, rpadilla@uccs.edu, Jorge A. Cantu, jcantu@uccs.edu, Daniel E. Torres, dtorres@uccs.edu, and Allen M. Schoffstall, amschoff@uccs.edu. Department of Chemistry, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918
Several bicyclic isoxazoline derivatives have been obtained by 1,3-dipolar cycloaddition of their alkenyloximino ether precursors. Intramolecular 1,3-dipolar nitrile oxide (INOC) cycloadditions have proven to provide a convenient pathway for the synthesis of isoxazoline derivatives. Isoxazoline derivatives can be used to obtain stereoselective syntheses of functional derivatives such as beta-hydroxy ketones by reduction of the isoxazoline ring. The synthesis of isoxazolines involves a two-step process in which the alkenyloximino ether is made in the first step by reduction of a beta-nitroalkene in the presence of an unsaturated alcohol. An INOC reaction in the second step produces a bicyclic isoxazoline. We have studied the substitution reactions of bicyclic isoxazolines, including the benzylic bromination. Our objectives are to improve the methodology used to produce the isoxazoline derivatives and to extend the study of their chemistry in other reactions.