Phosphorus pentachloride → 2-Chloro-5-phenylbenzoxazole

HRID 2116703Notes

Reaction equation

HRID 2116703 reaction equation
[C:1]1([C:7]2[CH:8]=[CH:9][C:10]3[O:14][C:13](=S)[NH:12][C:11]=3[CH:16]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.P(Cl)(Cl)(Cl)(Cl)[Cl:18]>P(Cl)(Cl)(Cl)=O>[Cl:18][C:13]1[O:14][C:10]2[CH:9]=[CH:8][C:7]([C:1]3[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=3)=[CH:16][C:11]=2[N:12]=1

Participants

4

Reactant 2

HCID 24819Phosphorus pentachlorideHCID 30326635-Phenyl-2(3H)-benzoxazolethione

Product 1

HCID 141698182-Chloro-5-phenylbenzoxazoleYield 640.1%

Reagents, catalysts & solvents 1

HCID 24813Phosphorus oxychlorideSolvent

Procedure

5-Phenyl-3H-benzooxazole-2thione (227 mg, 1.0 mmol) was dissolved in phosphorus oxychloride (1.6 mL). Phosphorus pentachloride (208 mg, 1.0 mmol) was added and the mixture was placed in an oil bath at 100° C. for 3 h. The mixture was allowed to cool to RT and concentrated. The crude residue was concentrated from CH2Cl2 (3×). The crude reaction product was triturated with hexanes (40 mL), and the resulting solids were collected by filtration. The solids were washed with hexanes (20 mL×3) and dried to afford 1.47 g (73%) of the title compound: 1H NMR (CDCl3, 400 MHz) δ 7.86 (d, 1H, J=1.3 Hz), 7.60-7.56 (m, 3H), 7.55-7.52 (m, 1H), 7.49-7.44 (m, 2H), 7.40-7.36 (m, 1H), 13C NMR (CDCl3, 100 MHz) δ 151.6, 151.4, 141.9, 140.7, 139.3, 129.2, 127.8, 127.7, 125.2, 118.4, 110.7; MS (Cl) m/z 230.1 (M+1); HPLC retention time=5.41 min.

Workup

  1. concentrationconcentrated
  2. concentrationThe crude residue was concentrated from CH2Cl2 (3×)
  3. customThe crude reaction product
  4. customwas triturated with hexanes (40 mL)
  5. filtrationthe resulting solids were collected by filtration
  6. washThe solids were washed with hexanes (20 mL×3)
  7. customdried

Sources & evidence

ORD record
ord-856bcc1ead294df3894821a56b146929
Source dataset
uspto-grants-2008_10
Patent number
US07439236B2

Reaction notes

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