Chiral phosphito-thioether complexes of palladium(0). Comments on the Pd, Rh, and Ir regio-and-enantioselective allylic alkylations of PhCH=CHCH(OAc)R, R = H, Me, Et

The new chiral auxiliary (R)-2-ethylthio-1-(phenylethyl)-(R)-binaphthyl phosphite, 1, and three stable Pd(0) olefin complexes containing this chelate, 2-4, have been synthesized. The structure of the maleic anhydride complex 3 has been determined by X-ray diffraction methods. Solution details for 2-4 and aspects of their dynamics have been elucidated via 2-D NMR spectroscopy. The fumaronitrile complex 2 exchanges intramolecularly, whereas the maleic anhydride and pentenedione derivatives, 3 and 4, respectively, exchange intermolecularly. Ligand 1 has been used as auxiliary in the Pd, Rh, and Ir regio- and enantioselective allylic alkylation reactions of PhCH=CHCH(OAc)R, R = H, Me, Et, with the anion of dimethyl malonate. Modest to good selectivities are reported.