COAP‐Pd Catalyzed Asymmetric Formal [3+2] Cycloaddition for Optically Active Multistereogenic Spiro Cyclopentane‐Indandiones Bearing Cyclic N‐Sulfonyl Ketimine Skeletons.

We reported a chiral oxamide‐phosphine ligand (COAP−Ph)‐Pd‐catalyzed asymmetric [3+2] cycloaddition reaction between vinyl cyclopropane compounds derived from 1,3‐indanedione and 2‐vinylcyclopropane‐1,1‐dicarboxylates with cyclic sulfonyl 1‐azadienes. The corresponding reactions provided a series of enantiomerically active spiro cyclopentane‐indandione and cyclopentane structures bearing three consecutive stereogenic centers in good yields with good diastereo‐ and enantioselectivity. The COAP−Pd complex serves not only to promote generation of chiral π‐allyl‐palladium intermediates and induce the asymmetry of the reaction, but also depress the background reaction. [ABSTRACT FROM AUTHOR]