Lawesson's reagent → (S)-tert-butyl 2-methyl-5-thioxopiperazine-1-carboxylate

HRID 576726Notes

Reaction equation

HRID 576726 reaction equation
[CH3:1][C@H:2]1[CH2:7][NH:6][C:5](=O)[CH2:4][N:3]1[C:9]([O:11][C:12]([CH3:15])([CH3:14])[CH3:13])=[O:10].COC1C=CC(P2(SP(C3C=CC(OC)=CC=3)(=S)S2)=[S:25])=CC=1>>[CH3:1][C@H:2]1[CH2:7][NH:6][C:5](=[S:25])[CH2:4][N:3]1[C:9]([O:11][C:12]([CH3:15])([CH3:14])[CH3:13])=[O:10]

Participants

3

Reactant 2

HCID 87949Lawesson's reagentHCID 90402439tert-butyl (2S)-2-methyl-5-oxopiperazine-1-carboxylate

Product 1

HCID 90402252(S)-tert-butyl 2-methyl-5-thioxopiperazine-1-carboxylateYield 148.2%

Conditions

Temperature
80 °C

Procedure

To a suspension of (S)-tert-butyl 2-methyl-5-oxopiperazine-1-carboxylate (7.0 g, 32.7 mmol) was added Lawesson's reagent (6.9 g, 16.7 mmol) and the reaction mixture was heated to 80° C. for 2 hours. The reaction mixture was cooled to room temperature, concentrated onto silica gel and purified by flash column chromatography (0-100% 10% 4M NH3 in MeOH in DCM) to provide the desired compound (5.7 g, 76%). 1H NMR (400 MHz, DMSO) δ 10.64 (s, 1H), 4.48 (d, J=18.9 Hz, 1H), 4.31-4.14 (m, 1H), 4.06 (d, J=18.9 Hz, 1H), 3.49-3.41 (m, 1H), 3.13 (ddd, J=13.7, 4.8, 2.9 Hz, 1H), 1.43 (s, 9H), 1.07 (d, J=6.6 Hz, 3H).

Workup

  1. temperatureThe reaction mixture was cooled to room temperature
  2. concentrationconcentrated onto silica gel
  3. custompurified by flash column chromatography (0-100% 10% 4M NH3 in MeOH in DCM)

Sources & evidence

ORD record
ord-3968751b176240f7b52b6cde000a30d0
Source dataset
uspto-grants-2015_05
Patent number
US09040534B2

Reaction notes

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