Efficient synthesis of carbazolespirooxindole skeletons via asymmetric Diels-Alder reaction of 3-vinylindoles and methyleneindolinones.

A highly efficient catalytic asymmetric Diels-Alder reaction between 3-vinylindoles and methyleneindolinones has been achieved using chiral N,N'-dioxide-Ni(II) complexes as the catalysts. A wide variety of substrates were readily tolerated, generating exclusively the corresponding exo-carbazolespirooxindole derivatives in excellent yields with high enantiomeric excesses (up to 98% yield, >99 : 1 d.r., and 98% ee) under mild reaction conditions.