Phosphorus oxychloride → Ethyl 2-chloro-4-(5-chloro-2-thienyl)-5-oxazolebutanoate

HRID 747429Notes

Reaction equation

[Cl:1][C:2]1[S:6][C:5]([C:7]2[NH:8][C:9](=O)[O:10][C:11]=2[CH2:12][CH2:13][CH2:14][C:15]([O:17][CH2:18][CH3:19])=[O:16])=[CH:4][CH:3]=1.P(Cl)(Cl)([Cl:23])=O>N1C=CC=CC=1>[Cl:23][C:9]1[O:10][C:11]([CH2:12][CH2:13][CH2:14][C:15]([O:17][CH2:18][CH3:19])=[O:16])=[C:7]([C:5]2[S:6][C:2]([Cl:1])=[CH:3][CH:4]=2)[N:8]=1

Participants

Conditions

Temperature: 125 °C

Procedure

A mixture of ethyl 4-[4-(5-chloro-2-thienyl)-2-oxo-4-oxazolin-5-yl]butanoate (12.5 g), phosphorus oxychloride (24.5 g) and pyridine (3.16 g) was heated to 120-130° C. and stirred for 45 minutes. The reaction mixture was poured into ice-water (200 ml) and extracted with ethyl acetate (150 ml×2). The organic layer was washed in sequence with a 10% aqueous solution of sodium hydrogen carbonate (100 ml) and a saturated aqueous solution of sodium chloride (100 ml) and dried over anhydrous magnesium sulfate. The organic layer was concentrated, the residue was subjected to silica gel column chromatography, and ethyl 2-chloro-4-(5-chloro-2-thienyl)-5-oxazolebutanoate was obtained as a yellow oil (5.79 g, 48%) from an ethyl acetate-hexane (1:4, v/v)-eluted fraction.

Workup

extractionextracted with ethyl acetate (150 ml×2)
washThe organic layer was washed in sequence with a 10% aqueous solution of sodium hydrogen carbonate (100 ml)
dry with materiala saturated aqueous solution of sodium chloride (100 ml) and dried over anhydrous magnesium sulfate
concentrationThe organic layer was concentrated

Sources & evidence

ORD record: ord-997f39b5e4864f6c85380d19d258f9c8
Source dataset: uspto-grants-2008_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07396848B1

Reaction notes

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