The stereoelectronic interaction in the starting material is the n(O) → σ*(Ccarbonyl–Caryl). The electron withdrawing substituent on the benzene ring will deplete the electron density on the aromatic ring and thus makes the σ*(Ccarbonyl–Caryl(nnitrile)) orbital a better acceptor than σ*(Ccarbonyl–Caryl(methoxy)) and these two stereoelectronic interactions would use different lone pairs on the oxygen atom. Also, the better the stereoelectronic interaction is, the less reactive to coordinate to the boron atom. This would result the intermediate to coordinate boron atom with the oxygen lone pair syn to the nitrile-aryl group.