Regio- and stereo-selective construction of cis-indeno[1,2-c]isoxazoles via a C–H allylation/1,3-dipolar cycloaddition cascade

Abstract

Combining rhodium-catalyzed C–H allylation with intramolecular 1,3-dipolar cycloaddition consistently yields bridged [n.2.1] isoxazolidines via intermediates bearing activated dienophiles. In the current work, this protocol was used to install a non-activated Z-alkene unit into the nitrone substrate, resulting in the access of fused cis-indeno[1,2-c]isoxazoles with excellent regio- and stereo-selectivity levels. A wide scope was demonstrated for nitrones including for those derived from natural products and pharmaceutical molecules. Derivatizations of the representative products were conducted to provide diverse important skeletons.