L-Cysteine, methyl ester → Methyl 2-(4'-carboxy-4'-phthalimidobutyl)-4(R)-thiazolidinecarboxylate

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Reaction Steps

A solution of L-cysteine methyl ester (1.71 g) and 5-formyl-2(S)-phthalimidopentanoic acid (3.49 g) in 120 ml of tetrahydrofuran was stirred under nitrogen for 2.5 hours and then taken to dryness to yield a white foam. This residue was dissolved in 250 ml of chloroform and washed with water (2×30 ml). The combined aqueous layers were back extracted with chloroform (2×30 ml). The organic layers were dried (Na2SO4) and then concentrated in vacuo to give a white foam, 4.83 g. Tlc on silica [4:1 Ethyl acetate:acetic acid] indicated a major spot at Rf =0.72. Exact mass measurement showed a molecular ion at 392.1024 (calcd. 392.1041). 'H NMR spectrum (CDCl3) showed a multiplet at δ7.72 (4H) and a singlet at δ3.78(3H).

Provenance & Evidence