Structural requirements in chiral diphosphine-rhodium complexes. II. N.M.R. determination of E,Z-geometry in prochiral substrates used in asymmetric hydrogenation reactions: α-acetamidocinnamic acids,esters, and parent azlactones.

Using n.m.r. the configuration of the stable 4-benzylidene-2-methyl-2-oxazolin-5-one, substituted derivatives, and the corresponding acids and esters derived from the parent stable azlactones were all found to be of Z-stereochemistry.