Synthesis of a novel chiral binaphthyl phospholane and its application in the highly enantioselective hydrogenation of enamides.

[formula: see text] A new chiral phosphine, (R,R)-1,2-bis[(R)-4,5-dihydro-3H-dinaphtho[2,1- c:1',2'-e]phosphepino]benzene [abbreviated as (R,R)-binaphane] was prepared on the basis of a practical route from a readily accessible enantiomerically pure binaphthanol. This ligand possesses both binaphthyl chirality and phospholane functionality. Excellent enantioselectivities (95-99.6% ee) have been observed in hydrogenation of an isomeric mixture of (E)- and (Z)-beta-substituted-alpha-arylenamides by using a Rh-binaphane catalyst. These enantioselectivities are the highest reported to date for this transformation.