Disclosed are processes for the preparation of enantiomerically-enriched cyclopropylalanine derivatives by the hydrogenation of certain enamides in the presence of a catalyst comprising a transition metal and a substantially enantiomerically-pure bis-phosphine catalyst and certain novel enamide ester compounds which are intermediates in the processes. The processes include novel 2-step and 3-step processes for the preparation of enantiomerically-enriched cyclopropylalanine derivatives. The two-step process comprises the steps of reacting cyclopropanecarboxaldehyde with a substituted phosphorylglycine to afford an enamide ester which then is hydrogenated in the presence of a catalyst comprising a transition metal and a substantially enantiomerically-pure bis-phosphine catalyst. The three-step process comprises the steps of forming an azlactone from an N-acylglycine and cyclopropanecarboxaldehyde, converting the azlactone to the aforesaid enamide which then is hydrogenated in the presence of a catalyst comprising a transition metal and a substantially enantiomerically-pure bis-phosphine catalyst.