Atropodiastereoselective C-H Olefination of Biphenyl p-Tolyl Sulfoxides with Acrylates
Résumé
A stereoselective method for the synthesis of axially chiral biaryl scaffolds by C-H bond functionalization was accomplished using chiral sulfoxide both as the directing group enabling the regioselective activation of a C-H bond and as the chiral auxiliary generating an asym. environment in the coordination sphere of the metal complex. We have demonstrated the directing ability of the p-tolylsulfinyl group in promoting the Pd(II)-catalyzed C-H olefination of biphenyls. Thus, reacting biphenyl p-tolyl sulfoxide I (R = H) as a mixt. of atropisomers with Me acrylate in the presence of Pd(OAc)2 gave coupling product I [R = (E)-CH:CHCO2Me] in 87% yield (4.6:1 d.r. SaR:SaS).