alpha-Bromoisovaleric acid, (R)- → (S)-2-benzoylthio-3-methylbutanoic acid

HRID 409188Notes

Reaction equation

HRID 409188 reaction equation
Br[C@H:2]([CH:6]([CH3:8])[CH3:7])[C:3]([OH:5])=[O:4].[C:9]([O-:17])(=[S:16])[C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=1.[Cs+]>CN(C=O)C.CCOCC>[C:9]([S:16][C@@H:2]([CH:6]([CH3:8])[CH3:7])[C:3]([OH:5])=[O:4])(=[O:17])[C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=1

Participants

5

Reactant 2

HCID 156968alpha-Bromoisovaleric acid, (R)-HCID 23707493Cesium thiobenzoate

Product 1

HCID 57454456(S)-2-benzoylthio-3-methylbutanoic acidYield 72.6%

Reagents, catalysts & solvents 2

HCID 3283Diethyl EtherSolventHCID 6228DimethylformamideSolvent

Procedure

To a solution of (R)-(+)-2-bromo-3-methylbutyric acid (4.20 g, 23.2 mmol) in DMF (41 mL) was added cesium thiobenzoate (6.08 g, 22.5 mmol). The mixture was stirred at rt for 20 h. The resulting solution was diluted with ether (200 mL) and washed with H2O (4×40 mL). The ethereal layer was dried (Na2SO4), and concentrated. The crude residue was recrystallized from hexanes to afford (S)-2-benzoylthio-3-methylbutanoic acid as a pale yellow solid (3.89 g, 72%); 1H NMR (300 MHz, CDCl3) δ 1.09 (d, J=7.4 Hz, 3H), 1.11 (d, J=7.4 Hz, 3H), 2.40 (m, 1H), 4.37 (d, J=5.9 Hz, 1H), 7.45 (t, J=7.4 Hz, 2H), 7.57 (t, J=7.4 Hz, 1H), 7.97 (d, J=7.4 Hz, 2H), 12.0 (br s, 1H); 13C NMR (75 MHz, CDCl3) δ19.8, 20.6, 30.5, 53.1, 127.6, 128.8, 133.9, 136.3, 177.9, 190.3; IR (neat) 3100, 2967, 1709, 1669 cm−1; [α]D22=−94.2 (c 1, CH2Cl2).

Workup

  1. washwashed with H2O (4×40 mL)
  2. dry with materialThe ethereal layer was dried (Na2SO4)
  3. concentrationconcentrated
  4. customThe crude residue was recrystallized from hexanes

Sources & evidence

ORD record
ord-14fd1036b82c44aea9866564a052f672
Source dataset
uspto-grants-2014_06
Patent number
US08759378B2

Reaction notes

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