(2S)-2-Bromo-3-methylbutanoic acid → (R)-2-benzoylthio-3-methylbutanoic acid

HRID 508135Notes

Reaction equation

HRID 508135 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 179487(2S)-2-Bromo-3-methylbutanoic acidHCID 23707493Cesium thiobenzoate

Product 1

HCID 13662423(R)-2-benzoylthio-3-methylbutanoic acidYield 75.5%

Reagents, catalysts & solvents 2

HCID 3283Diethyl EtherSolventHCID 6228DimethylformamideSolvent

Procedure

To a solution of (S)-(−)-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 (R)-2-benzoylthio-3-methylbutanoic acid as a pale yellow solid (4.05 g, 75%); 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), 11.9 (br s, 1H); 13C NMR (75 MHz, CDCl3) δ 19.8, 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=+95.6 (c 1, CH2Cl2). All spectral data was identical to that previously published (Strijtveen, B.; Kellogg, R. M. J. Org. Chem. 1986, 51, 3664).

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-2362a4e5d24f45539b32b7995da752fc
Source dataset
uspto-grants-2015_08
Patent number
US09095565B2

Reaction notes

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