Diastereotopic differentiation on phosphorus templates via the ring-closing metathesis reaction.

[reaction: see text] A strategy is described in which the ring-closing metathesis reaction is utilized to desymmetrize a number of pseudo-C(2)-symmetric phosphorus templates 1-3. These reactions give excellent levels of selectivity (12-15:1) with vinyl phosphonamides containing a (E)-Ph group on the diastereotopic olefins. This approach is being developed as an effective method of obtaining P-chiral phosphonamides and phosphonates.