M. Sakurai et al., A NEW SYNTHETIC ROUTE FOR THE GAMMA-LACTONE PRECURSORS OF HYDROXYETHYLENE DIPEPTIDE ISOSTERES, Tetrahedron letters, 34(37), 1993, pp. 5939-5942
Delta-Phthalimido-gamma-ketoesters were obtained by the Pd catalyzed c
oupling reaction between acid chlorides and organozinc reagents derive
d from beta-iodoesters, and were converted into the gamma-lactone prec
ursors of Phe-psi[H.E.]-Ala and Phe-psi[H.E.]-Pro (15a,b-18a,b).