Réaction #595318

Équation de réaction

(R)-(+)-2-bromo-3-methylbutyric acid

cesium thiobenzoate

→

(S)-2-benzoylthio-3-methylbutanoic acid

Rendement 72.6%

Solvants

ether

DMF

Conditions de réaction

Traitement

1. 1
   Lavagewashed with H2O (4×40 mL)
2. 2
   SéchageThe ethereal layer was dried (Na2SO4)
3. 3
   Concentrationconcentrated
4. 4
   AutreThe crude residue was recrystallized from hexanes

Mode opératoire

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) 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=−94.2 (c 1, CH2Cl2).

Source