Pyridine → Methyl 4-bromo-5-cyanofuran-2-carboxylate

To a solution of 46.55 g (0.20 mol) of methyl 4-bromo-5-formyl-2-furoate in 465 mL of acetonitrile was added 15.28 g (0.22 mol) of hydroxylamine hydrochloride. To this suspension 96.6 mL (1.2 mol) of pyridine was added dropwise over a period of 35 min, at 20-25° C. After 90 min stirring neat trifluoroacetic anhydride (67.72 mL, 0.48 mol) was dropped in over 45 min at room temperature. After 2.5 hours stirring the reaction mass was poured in a mixture of HCl 1 M (0.75 L) and ethyl acetate (0.75 L); the aqueous layer was extracted again with 0.45 L of ethyl acetate. The organic extracts were washed with 0.45 L of 2 M HCl and the aqueous layer was back extracted with 0.3 L of ethyl acetate. The combined organic extracts were concentrated under reduced pressure to dryness. This crude material was dissolved in 100 mL of ethanol 95° and treated dropwise with 150 mL of water under efficient stirring at 40°-45° C. The resulting suspension was cooled to 0/+4° C. for 1 hour then filtered to afford, after drying, 44.2 g of product as light cream solid.

1. additionwas dropped in over 45 min at room temperature
2. extractionthe aqueous layer was extracted again with 0.45 L of ethyl acetate
3. washThe organic extracts were washed with 0.45 L of 2 M HCl
4. extractionthe aqueous layer was back extracted with 0.3 L of ethyl acetate
5. concentrationThe combined organic extracts were concentrated under reduced pressure to dryness
6. dissolutionThis crude material was dissolved in 100 mL of ethanol 95°
7. additiontreated dropwise with 150 mL of water
8. stirringunder efficient stirring at 40°-45° C
9. temperatureThe resulting suspension was cooled to 0/+4° C. for 1 hour
10. filtrationthen filtered
11. customto afford
12. customafter drying

ORD-Eintrag

ord-20185e2a1b1c49339e5ed555136f41ca

Quelldatensatz

uspto-grants-2009_02

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07485661B2