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

HRID 609651Notes

Reaction equation

HRID 609651 reaction equation
[CH2:1]([N:8]1[CH2:13][CH2:12][N:11]([C:14]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])=[O:15])[CH2:10][C:9]1=O)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.COC1C=CC(P2(=S)SP(=S)(C3C=CC(OC)=CC=3)[S:31]2)=CC=1>C1(C)C=CC=CC=1>[CH2:1]([N:8]1[CH2:13][CH2:12][N:11]([C:14]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])=[O:15])[CH2:10][C:9]1=[S:31])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

4

Reactant 2

HCID 87949Lawesson's reagentHCID 10891590Tert-butyl 4-benzyl-3-oxopiperazine-1-carboxylate

Product 1

HCID 195997511-Benzyl-4-(tert-butyloxycarbonyl)piperazin-2-thioneYield 132.6%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

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).

Workup

  1. temperatureThe mixture was cooled
  2. customthen partitioned between EtOAc (3×50 mL) and water (50 mL)
  3. dry with materialThe combined organic layers were dried (Na2SO4)
  4. customevaporated
  5. customThe residue was chromatographed on silica gel
  6. washeluting with CH2Cl2 :EtOAc (100:0→95:5→90:10)

Sources & evidence

ORD record
ord-c4346a7bb9974da6801bd88ede4148ac
Source dataset
uspto-grants-1999_12
Patent number
US05998415

Reaction notes

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