Synthesis and Optical Resolution of Aminophosphines with Axially Chiral C(aryl)−N(amine) Bonds for Use as Ligands in Asymmetric Catalysis
2006-09-15T00:00:00Z (GMT) by
<i>N</i>-Aryl indoline-type aminophosphines <b>1a</b>−<b>c</b> were obtained in good yields by a nucleophilic aromatic substitution (S<sub>N</sub>Ar) reaction followed by silane reduction. Aminophosphine <b>1d</b> was also prepared from 2,3-difluorobenzaldehyde (<b>4</b>) via dimethylhydrazone. Optical resolution of C(aryl)−N(amine) bond atropisomers was achieved using (<i>S</i>)-(+)-di-μ<i>-</i>chlorobis[2-[(dimethylamino)ethyl]phenyl-<i>C</i><sup>2</sup>,<i>N</i>]dipalladium(II) ((<i>S</i>)-<b>10</b>). The determination of absolute configuration and the investigation of the rotation barrier for C(aryl)−N(amine) bond axial stability of an aminophosphine <b>1 </b>are described. Finally, the ability of the chiral phosphine ligand <b>1</b> is demonstrated in a catalytic asymmetric reaction, such as a palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate (up to 95% ee).