Enantioselective synthesis of pseudotripeptides incorporating a γ-methylene derivative of 2,6-diaminopimelic acid:: Part 6

An efficient enantioselective synthesis of pseudotripeptides 5, 8a-d and 13a and b incorporating a 2,6-diamino-4-methylene-1,7-heptandioic acid residue, has been accomplished starting from the glycine derived chiral synthon 1 (from L-valine). The absolute configuration of the new stereocentres was assigned on the basis of H-1 NMR spectra. The geometry of derivative 4 was deduced on the basis of H-1 NMR parameters (delta(NH) value, temperature coefficient, delta(NH) change upon addition of DMSO or CD3OD, NOE studies) and IR spectra. (C) 2004 Elsevier Ltd. All rights reserved.