Pd-Catalyzed Sequential Electrophilic Cyclization/Selective C–H Annulation Cascade: Synthesis of Isoxazole-Phthalimide-Fused Poly-Heterocyclics
V. Suresh, T Mahipal Reddy, Dattatri, Maddi Sridhar Reddy
Abstract
Harnessing the organo-palladium intermediates generated from electrophilic cyclizations for tandem C-C bond construction is a challenging task but constitutes an excellent tool for constructing complex motifs from simpler substrates. We realize herein such a cyclative annulation of alkynyl-oxime ethers with maleimides for the facile construction of isoxazole-phthalimide hybrid motifs through Pd(II) catalysis. This protocol features excellent regio-selectivity in C-H selection, a broad substrate scope, good functional group tolerance, and scalability. Necessary KIE & labeling studies give insight into the reaction mechanism.
Topics & Concepts
ChemistryPhthalimideAnnulationIsoxazoleElectrophileCascadeCatalysisCombinatorial chemistryStereochemistryOrganic chemistryChromatographyCatalytic C–H Functionalization MethodsCatalytic Cross-Coupling ReactionsSynthesis and Catalytic Reactions