Highly Stereoselective Co(III)-Catalyzed Three-Component C–H Bond Addition Cascade

A highly stereoselective three-component C(sp 2 )–H bond addition across alkene and polarized π-bonds is reported for which Co(III) catalysis was shown to be much more effective than Rh(III). The reaction proceeds at ambient temperature with both aryl and alkyl enones employed as efficient coupling partners. Moreover, the reaction exhibits extremely broad scope with respect to the aldehyde input with electron rich and poor aromatic, alkenyl, and branched and unbranched alkyl aldehydes all coupling in good yield and with high diastereoselectivity. Multiple directing groups participate in this transformation, including pyrazole, pyridine, and imine functionalities. Both aromatic and alkenyl C(sp 2 )–H bonds undergo the three-component addition cascade, and the alkenyl addition product can readily be converted to diastereomerically pure 5-membered lactones. Additionally, the first asymmetric reactions with Co(III)-catalyzed C–H functionalization are demonstrated with three-component C–H bond addition cascades employing N - tert -butanesulfinyl imines. These examples represent the first transition metal catalyzed C–H bond additions to N - tert -butanesulfinyl imines, which have proven to be versatile and extensively used intermediates for the asymmetric synthesis of amines. A highly stereoselective three-component C(sp 2 )–H bond addition across alkene and polarized π-bonds is reported. Co(III) catalysis was much more effective than Rh(III) providing products in good yield and with high diastereoselectivity for an extremely broad range of aldehydes. Additionally, the first asymmetric reactions employing Co(III)-catalyzed C–H functionalization are reported for three-component C–H bond addition cascades with N - tert -butanesulfinyl imines.