“Organo–Metal” Synergistic Catalysis: The 1+1>2 Effect for the Construction of Spirocyclopentene Oxindoles

Synergy in action : A highly efficient “organo–metal” synergistic catalysis strategy for the synthesis of spirocyclopentene oxindole derivatives has been developed (see scheme). The lower overall d.r. and ee obtained from the stepwise approach (4:1 vs. 8:1 d.r.; 71 vs. >99 % ee ) suggest that both catalysts function more efficiently when combined, compared with the separate catalytic approach, and show an evident 1+1>2 synergistic effect for the construction of spirocyclopentene oxindoles.