Urea → 5-Benzyloxazol-2-amine

A mixture of 2-bromo-3-phenylpropionaldehyde (14.2 g, crude from above) and urea (7.2 g, 0.12 mol) were heated to reflux for 15 hours in 200 mL of ethanol. The solvent was evaporated to dryness and the residue was diluted with dichloromethane (250 mL) and then washed with sodium hydroxide (10% aqueous solution, 100 mL) and water (50 mL). The organic layer was extracted three times with hydrochloric acid (5% aqueous solution, 250 mL). The combined aqueous layers were brought to pH 9 to 10 with a 10% aqueous solution of sodium hydroxide and then extracted three times with dichloromethane (300 mL). The organic layer was dried over sodium sulfate, evaporated to dryness, and purified by silica gel column chromatography to give a pale yellow solid. (1.6 g, 9.2 mmol, 9.2% from 3-phenyl-propionaldehyde). ESI-MS m/z calc. 174.1. found; 175.1 1H NMR (CDCl3) δ 7.32-7.22 (m, 5H), 6.39 (s, 1H), 4.72 (bs, 2H), 3.84 (s, 2H).

1. temperaturewere heated
2. customThe solvent was evaporated to dryness
3. additionthe residue was diluted with dichloromethane (250 mL)
4. washwashed with sodium hydroxide (10% aqueous solution, 100 mL) and water (50 mL)
5. extractionThe organic layer was extracted three times with hydrochloric acid (5% aqueous solution, 250 mL)
6. extractionextracted three times with dichloromethane (300 mL)
7. dry with materialThe organic layer was dried over sodium sulfate
8. customevaporated to dryness
9. custompurified by silica gel column chromatography
10. customto give a pale yellow solid

ORD record

ord-d6eaa27c7bd7402bbd233094a0bdc9c6

Source dataset

uspto-grants-2014_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08759335B2