Methacryloyl chloride → 1-(2-Methylacryloyl)-L-proline

A mechanically stirred mixture of L-proline (42.0 grams, g), NaHCO3 (148 g), H2O (680 milliliters, ml) and diethyl ether (280 ml) was maintained in an ambient temperature bath at pH 10.5-10.7 (adjusted by the addition of concentrated aqueous NaOH), then treated portionwise over 20 minutes with a solution of redistilled methacryloyl chloride (40 ml) in diethyl ether (20 ml). Additional concentrated aqueous NaOH was added as needed to keep the pH at 10.5-10.7. Upon addition of all of the methacryloyl chloride (and pH stabilization), the mixture was stirred for 20 minutes at ambient temperature. The resulting immiscible phases were separated and the aqueous phase was extracted with two 250 ml portions of diethyl ether. The combined organic extracts were washed with H2O (50 ml), and the aqueous extract was added to the aqueous phase which phase was then acidified to pH 1 with concentrated aqueous HCl and then extracted with four 250 ml portions of ethyl acetate. The combined ethyl acetate extracts were washed with about 100 ml of brine (saturated aqueous sodium chloride solution) and then dried over Na2SO4. The resulting solution was filtered and concentrated in vacuo to about 230 ml and then heated to boiling, diluted with hexane (80 ml) and allowed to cool. Upon cooling, the desired N-methacryloyl-L-proline spontaneously crystallized as chunky white prisms (51.3 g). The concentrated mother liquor yielded a second crop of crystals (4.26 g) when crystallized as described above. A portion of the first crop was recrystallized twice from ethyl acetate to give an analytical sample, m.p. 102°-104.5° C., having the following spectral characteristics:

1. customThe resulting immiscible phases were separated
2. extractionthe aqueous phase was extracted with two 250 ml portions of diethyl ether
3. washThe combined organic extracts were washed with H2O (50 ml)
4. extractionthe aqueous extract
5. additionwas added to the aqueous phase which phase
6. extractionextracted with four 250 ml portions of ethyl acetate
7. washThe combined ethyl acetate extracts were washed with about 100 ml of brine (saturated aqueous sodium chloride solution)
8. dry with materialdried over Na2SO4
9. filtrationThe resulting solution was filtered
10. concentrationconcentrated in vacuo to about 230 ml
11. temperatureheated
12. additiondiluted with hexane (80 ml)
13. temperatureto cool
14. temperatureUpon cooling
15. customthe desired N-methacryloyl-L-proline spontaneously crystallized as chunky white prisms (51.3 g)

ORD record

ord-a1025c83f7fd4244af8db2b77f793178

Source dataset

uspto-grants-1986_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04633025