Lawesson's reagent → tert-Butyl (S)-5-thioxo-2-pyrrolidinecarboxylate

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Reaction Steps

To a solution of t-butyl pyroglutamate (1a) (10.12 g, 54.6 mmol) in benzene (250 mL), was added Lawesson's reagent (11.05 g, 27.3 mmol). The mixture was stirred at reflux for 15.5 h, then concentrated. The resultant residue was purified by flash chromatography (0 to 2 to 3 to 4% MeOH/CHCl3) to afford 10.50 g (95%) of the title compound, 1b. 1H NMR (300 MHz, CDCl3) δ 7.27 (br s, 1H), 4.46–4.39 (m, 1H), 3.03–2.84 (m, 2H), 2.58–2.46 (m, 1H), 2.37–2.23 (m, 2H), 1.49 (s, 9H).

Provenance & Evidence