[C:1]([O-])(=[O:5])[CH:2]([CH3:4])[OH:3].[Na+].C1(P(N=[N+]=[N-])(C2C=CC=CC=2)=O)C=CC=CC=1.C(N(CC)CC)C.Cl.[NH:33]1[CH2:47][CH2:46][CH2:45][C@H:34]1[C:35]([O:37][CH2:38][C:39]1[CH:44]=[CH:43][CH:42]=[CH:41][CH:40]=1)=[O:36]>CN(C=O)C>[OH:3][C@@H:2]([CH3:4])[C:1]([N:33]1[CH2:47][CH2:46][CH2:45][C@H:34]1[C:35]([O:37][CH2:38][C:39]1[CH:40]=[CH:41][CH:42]=[CH:43][CH:44]=1)=[O:36])=[O:5]
A mixture of sodium lactate (1.7 g, 15.0 mmole), diphenyl phosphorylazide (3.6 ml, 16.5 mmole) and dry DMF (30 ml) at 0° C. (ice bath) in an argon atmosphere was treated with triethyl amine (2.1 ml, 15.2 mmole) and L-proline, phenylmethyl ester, hydrochloride salt (3.6 g, 15.0 mmole). After 24 hours, the reaction mixture was partitioned between EtOAc and H2O. The aqueous phase was back extracted, the organic extracts combined, washed with 5% KHSO4, brine, and evaporated. The residue (5.0 g) was chromatographed on silica (130 g) eluting with EtOAc/Hexane (1:1) to give the title compound (2.5 g, 9.0 mmole, 60% yield) as a white crystalline solid after evaporation, m.p. 86°-88° C.
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