A donor–acceptor cyclopropene as a dipole source for a silver(i) catalyzed asymmetric catalytic [3+3]-cycloaddition with nitrones

Silver(I)-catalyzed asymmetric formal [3+3]-cycloaddition of nitrones with a donor-acceptor cyclopropene, formed in situ from dirhodium acetate-catalyzed dinitrogen extrusion/intramolecular cyclization of enoldiazoacetates, effectively generates 3,6-dihydro-1,2-oxazine derivatives in high yield and with exceptional stereocontrol.