Hexamethylenetetramine → methyl 2-methyloxazole-4-carboxylate

Hexamethylenetetramine (11.7 g, 5.00 mmol) and 1,8-diazabicyclo(5,4,0)undec-7-ene were added to a stirred suspension of copper bromide (18.7 g, 83.85 mmol) in dichloromethane (50 mL) at 0° C. and purged with argon gas for 20 min. To the mixture was added methyl 2-methyl-4,5-dihydrooxazole-4-carboxylate (3 g, 20.97 mmol) at 0° C. The mixture was allowed to warm to ambient temperature and stirred for a further 12 h. The solvent was removed in vacuo and the resulting residue partitioned between ethyl acetate and 1:1 saturated aqueous ammonium chloride and ammonium hydroxide. The organic layer was separated and the aqueous layer extracted with ethyl acetate (2×20 mL). The combined organic layers were washed with 1:1 saturated aqueous ammonium chloride and ammonium hydroxide, 10% aqueous citric acid, saturated sodium bicarbonate solution, brine, dried over anhydrous sodium sulfate and concentrated in vacuo to afford methyl 2-methyloxazol-4-carboxylate (1.1 g, 34%) as a solid.

1. custompurged with argon gas for 20 min
2. customThe solvent was removed in vacuo
3. customthe resulting residue partitioned between ethyl acetate and 1:1 saturated aqueous ammonium chloride and ammonium hydroxide
4. customThe organic layer was separated
5. extractionthe aqueous layer extracted with ethyl acetate (2×20 mL)
6. washThe combined organic layers were washed with 1:1 saturated aqueous ammonium chloride and ammonium hydroxide, 10% aqueous citric acid, saturated sodium bicarbonate solution, brine
7. dry with materialdried over anhydrous sodium sulfate
8. concentrationconcentrated in vacuo

ORD record

ord-7719fc183bd54084b87bc52a40789057

Source dataset

uspto-grants-2015_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08993574B2