Lawesson's reagent → 1-Benzyl-4-(tert-butyloxycarbonyl)piperazin-2-thione

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Reaction Steps

A mixture of 1-benzyl-4-(tert-butyloxycarbonyl)piperazin-2-one (1.0 mg, 3.4 mmol) and 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulphide (Lawesson's Reagent) (837 mg, 2.1 mmol) were heated at 90° C. in toluene (10 mL), under nitrogen for 45 min. The mixture was cooled then partitioned between EtOAc (3×50 mL) and water (50 mL). The combined organic layers were dried (Na2SO4) and evaporated. The residue was chromatographed on silica gel, eluting with CH2Cl2 :EtOAc (100:0→95:5→90:10) to afford the title compound (853 mg, 82%) as a colourless solid. mp. 126-129° C. 1H NMR (250 MHz, CDCl3) δ 1.47 (9H, s), 3.40-3.44 (2H, m), 3.60-3.65 (2H, m), 4.67 (2H, s), 5.31 (2H, s), 7.31-7.39 (5H, m). MS (ES+) (307, M+1).

Provenance & Evidence