Efficient chirality switching in the asymmetric addition of indole to N-tosylarylimines in the presence of axially chiral cyclometalated bidentate N-heterocyclic carbene palladium(II) complexes

Efficient dual stereocontrol can be achieved by using axially chiral cyclometalated bidentate N-heterocyclic carbene palladium(II) complexes for the addition of indole to N-tosylarylimines simply by the adjustment of the R group on the benzene rings of the NHC–Pd(II) complexes.

Efficient dual stereocontrol can be achieved by using axially chiral cyclometalated bidentate N-heterocyclic carbene palladium(II) complexes in the asymmetric addition of indole to N-tosylarylimines just by the adjustment of the R group on the benzene rings of the NHC–Pd(II) complexes.Figure optionsDownload as PowerPoint slide

(R)-(+)-Axially chiral cyclometalated bidentate NHC–Pd(II) complex 1aC46H29ClN4PdEe = 100%[α]D20=+126.1 (c 0.95, CHCl3).Source of chirality: resolutionAbsolute configuration: (R)

(R)-(+)-Axially chiral cyclometalated bidentate NHC–Pd(II) complex 1bC46H33ClN4PdEe = 100%[α]D20=+247.6 (c 1.01, CHCl3)Source of chirality: resolutionAbsolute configuration: (R)

(R)-(+)-Axially chiral cyclometalated bidentate NHC–Pd(II) complex 1cC48H27ClF6N4PdEe = 100%[α]D20=+218.3 (c 1.08, CHCl3)Source of chirality: resolutionAbsolute configuration: (R)