Thionyl Chloride → methyl 2-methyloxazole-4-carboxylate

Temperature

0 °C

A solution of the respective 2-acetylamino-3-oxo-propionic acid methyl ester derivative (0.63 mmol, 1.0 eq.) in CHCl3 (0.4 mL) was cooled to 0° C. in an ice/NaCl bath. SOCl2 (0.88 mmol, 1.4 eq.) was added to the stirred solution and the temperature was maintained at 0° C. for 30 minutes. Then the solution was stirred and refluxed for one hour. Another 0.25 eq. of SOCl2 was added and the reaction mixture was refluxed for another hour. The excess SOCl2 was quenched with 1M aq. K2CO3. The aq. layer was extracted twice with ether. The combined organic phases were washed once with water and dried over MgSO4, filtered and concentrated yielding the corresponding 2-methyl-oxazole-4-carboxylic acid methyl ester derivative. The respective 2-methyl-oxazole-4-carboxylic acid methyl ester derivative was dissolved in a mixture of EtOH (0.7 ml) and 2N aq. NaOH (0.7 mL, 2.5 eq.). The mixture was stirred at rt for 2 hours. The reaction mixture was washed once with ether and this organic layer was discarded. The aq. layer was then acidified with conc. HCl and extracted twice with ether. Both organic layers were combined, dried over MgSO4 and concentrated in vacuo to afford the corresponding 2-methyl-oxazole-4-carboxylic acid derivatives.

1. temperaturerefluxed for one hour
2. temperaturethe reaction mixture was refluxed for another hour
3. customThe excess SOCl2 was quenched with 1M aq. K2CO3
4. extractionThe aq. layer was extracted twice with ether
5. washThe combined organic phases were washed once with water
6. dry with materialdried over MgSO4
7. filtrationfiltered
8. concentrationconcentrated

ORD record

ord-a5e7d05890d5428bba9174ced05ed7c8

Source dataset

uspto-grants-2012_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08236801B2