Pd-Catalyzed Divergent C(sp2)-H Activation/Cycloimidoylation of 2-Isocyano-2,3-diarylpropanoates.

A Pd-catalyzed site-selective C(sp2)-H activation/cycloimidoylation of 2-isocyano-2,3-diarylpropanoates to construct diverse cyclic imine products has been developed. Six-membered 3,4-dihydroisoquinolines containing a C3 quaternary carbon center were generated dominantly by using bulky Ad2P n-Bu as a ligand, while five-membered 1,1-disubstituted 1 H-isoindoles were formed preferentially in the presence of bidentate phosphine ligand DPPB. The selectivity for 1 H-isoindole formation was enhanced by using steric hindered aryl iodides. DFT calculations suggested that the experimentally observed ligand-controlled selectivity was a result of trans effect.