Nickel(ii)-catalyzed enantioselective cyclopropanation of 3-alkenyl-oxindoles with phenyliodonium ylide via free carbene† †Electronic supplementary information (ESI) available. CCDC 1038443 and 1038445. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc03658e Click here for additional data file. Click here for additional data file.

The catalytic asymmetric cyclopropanation of a C]C double bond provides efficient access to optically active cyclopropane derivatives that are essential motifs in natural products and valuable building blocks for various transformations. Chiral transition-metal-catalyzed carbene transfer, such as that using Cu(I)-, Rh(II)-, Ru(II)-, and Co(II)-complexes with diazo compounds, permits such cylcopropanations in high yields and selectivities. However, in view of the mild, selective and nontoxic characteristics of phenyliodonium ylides, they could provide an alternative to diazo precursors in the cyclopropanation. The asymmetric cyclopropanation of simple olens using phenyliodonium ylide was successfully developed, mainly with chiral [Rh2{(S)-nttl}4] and Cu(I)-bis(oxazoline)