Synthesis of 1'-(2-(diarylphosphino)1-naphthyl)isoquinolines; variation of the aryl substituent

A series of phosphinamines in which the aryl substituents are varied has been prepared from the known triflate 1 by palladium catalysed reaction with the appropriate secondary phosphine oxide followed by reduction with trichlorosilane. In four of the six cases attempted, resolution was successfully completed by fractional crystallisation of the diastereomeric cationic complexes formed with di-mu-chloro-bis[(R)-dimethyl(l-phenethyl)aminato-C-2,N]dipalladium, as previously described. The order of crystallisation was not predictable and in one case the specific rotation of the derived phosphine was anomalous, although the CD spectrum in the 220-350 nm region was as expected by comparison with the parent compound. (C) 1997 Elsevier Science Ltd.