A catalytic asymmetric construction of a tetrahydroquinoline-based spirooxindole framework via a diastereo- and enantioselective decarboxylative [4+2] cycloaddition

A catalytic asymmetric decarboxylative [4+2] cycloaddition of vinyl benzoxazinanones with methyleneindolinones has been established, which provided a series of chiral tetrahydroquinoline-based 3,3'-spirooxindoles in high yields (up to 96%) and with excellent diastereo- and enantioselectivities (all >95 : 5 d.r., up to 99% ee). This reaction not only represents the first example of catalytic enantioselective [4+2] cycloaddition between methyleneindolinones and Pd-containing 1,4-dipoles, but also demonstrates the great practicability of catalytic asymmetric decarboxylative cycloadditions in the synthesis of enantio-enriched polycyclic compounds.