Synthesis of novel isoxazoline-fused cispentacin stereoisomers

New isoxazoline-fused cispentacins were prepared by the 1,3-dipolar cycloaddition of nitrile oxides to beta-amino esters containing a cyclopentene skeleton. This synthetic procedure gave regio- and diastereoisomers of the cispentacins. The synthetic route was extended to the synthesis of these compounds in enantiomerically pure form. (C) 2009 Elsevier Ltd. All rights reserved.