Boron trifluoride etherate → Ethyl 4-ethylthiazole-5-carboxylate

Temperature

0 °C

To a 0° C. solution of ethyl 2-amino-4-ethyl-1,3-thiazole-5-carboxylate (4.0 g, 18.2 mmol) in anhydrous THF (65 mL) was added boron trifluoride diethyl etherate (3.2 mL, 25.5 mmol). After 15 minutes of stirring at 0° C. was added tert-butyl nitrite (10 mL, 84 mmol). The mixture was stirred at 0° C. for 3 hours before a solution of sodium hypophosphonate (6.4 g, 73 mmol) in water (20 mL) was added. The mixture was stirred at 0° C. for 2 hours and at room temperature overnight. The solution was basified to pH 8-9 with 5 N NaOH and was extracted with EtOAc (3×75 mL). The organic extracts were combined, dried over MgSO4, filtered, evaporated, and dried in vacuo, affording ethyl 4-ethyl-1,3-thiazole-5-carboxylate (3.19 g, 85% yield). The product was used without further purification.

1. additionwas added
2. stirringThe mixture was stirred at 0° C. for 2 hours and at room temperature overnight
3. extractionwas extracted with EtOAc (3×75 mL)
4. dry with materialdried over MgSO4
5. filtrationfiltered
6. customevaporated
7. customdried in vacuo

ORD record

ord-44b46648839240729090cae2d0443017

Source dataset

uspto-grants-2015_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09040538B2