Abstract: The present invention provides a method for making compound (1) by reacting compound (2) with phosphine oxide (3) in the presence of a transition metal/phosphine complex and optionally reducing the reaction product: ##STR1## where n represents 0 or 1; the double line having a continuous line and a dotted line represents a double bond or a single bond such that the ring having the double line forms a naphthalene ring or an octahydronaphthalene ring with an adjacent benzene ring; Tf represents a trifluoromethanesulfonyl group; and Ar represents a phenyl group, a substituted phenyl group or a naphthyl group. The present invention provides an economical way to produce compound (1) as a ligand of a complex useful as a catalyst for a variety of asymmetric synthesis reactions.

Abstract: A novel diphosphine compound of the formula (I): ##STR1## where R.sup.1 and R.sup.2 represent independently cycloalkyl, unsubstituted or substituted phenyl, or a five-membered heteroaromatic ring. The compound is useful as a ligand for an asymmetric reaction, in particular, as an asymmetric hydrogenation catalyst.