Adipic anhydride → 5-(4,5,7-Trifluorobenzothiazol-2-yl)pentanoic acid

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Reaction Conditions

Reaction Steps

A solution of adipic acid (10.0 g, 68 mmol) in acetic anhydride (50 ml) was heated to reflux for 3 hours. An excess of acetic anhydride was then distilled off in vacuo leaving adipic anhydride (7.4 g). 2-Amino-3,4,6-trifluorothiophenol (200 mg, 1.1 mmol) was dissolved in NMP (1 ml) under a nitrogen stream. To the resultant solution was gradually added adipic anhydride (143 mg, 1.1 mmol) and the mixture was stirred at 100° C. for 6 hours. After naturally cooling, the mixture was diluted with water and extracted with ethyl acetate. The organic phase was extracted with aqueous sodium bicarbonate. The alkaline phase was acidified with 10% hydrochloric acid and re-extracted with ethyl acetate. The combined organic phases were dried and then evaporated to yield a residue, which was recrystallized from acetonitrile to give 5-(4,5,7-trifluorobenzothiazol-2-yl)pentanoic acid (81 mg, 26%).

Provenance & Evidence