D-Proline → (2R)-1-Methacryloylpyrrolidin-2-carboxylic Acid

D-Proline, 14.93 g, 0.13 mol) was dissolved in 71 mL of 2 N NaOH and cooled in an ice bath; the resulting alkaline solution was diluted with acetone (71 mL). An acetone solution (71 mL) of methacryloyl chloride (13.56 g, 0.13 mol) and 2 N NaOH solution (71 mL) were simultaneously added over 40 min to the aqueous solution of D-proline in an ice bath. The pH of the mixture was kept at 10-11° C. during the addition of the methacryloyl chloride. After stirring (3 h, room temperature), the mixture was evaporated in vacuo at a temperature at 35-45° C. to remove acetone. The resulting solution was washed with ethyl ether and was acidified to pH 2 with concentrated HCl. The acidic mixture was saturated with NaCl and was extracted with EtOAc (100 mL×3). The combined extracts were dried over Na2SO4, filtered through Celite, and evaporated in vacuo to give the crude product as a colorless oil. Recrystallization of the oil from ethyl ether and hexanes afforded 16.2 (68%) of the desired compound as colorless crystals: mp 102-103° C. (lit. [214] mp 102.5-103.5° C.); the NMR spectrum of this compound demonstrated the existence of two rotamers of the title compound. 1H NMR (300 MHz, DMSO-d6) δ 5.28 (s) and 5.15 (s) for the first rotamer, 5.15 (s) and 5.03 (s) for the second rotamer (totally 2H for both rotamers, vinyl CH2), 4.48-4.44 for the first rotamer, 4.24-4.20 (m) for the second rotamer (totally 1H for both rotamers, CH at the chiral center), 3.57-3.38 (m, 2H, CH2), 2.27-2.12 (1H, CH), 1.97-1.72 (m, 6H, CH2, CH, Me); 13C NMR (75 MHz, DMSO-d6) δ for major rotamer 173.3, 169.1, 140.9, 116.4, 58.3, 48.7, 28.9, 24.7, 19.5: for minor rotamer 174.0, 170.0, 141.6, 115.2, 60.3, 45.9, 31.0, 22.3, 19.7; IR (KBr) 3437 (OH), 1737 (C═O), 1647 (CO, COOH), 1584, 1508, 1459, 1369, 1348, 1178 cm−1; [α]D26+80.8° (c=1, MeOH); Anal. Calcd. for C9H13NO3: C, 59.00; H, 7.15; N, 7.65. Found: C, 59.13; H, 7.19; N, 7.61.

1. temperaturecooled in an ice bath
2. customthe mixture was evaporated in vacuo at a temperature at 35-45° C.
3. customto remove acetone
4. washThe resulting solution was washed with ethyl ether
5. extractionwas extracted with EtOAc (100 mL×3)
6. dry with materialThe combined extracts were dried over Na2SO4
7. filtrationfiltered through Celite
8. customevaporated in vacuo
9. customto give the crude product as a colorless oil
10. customRecrystallization of the oil from ethyl ether and hexanes

ORD record

ord-6656df52d62e43a4ba8f2b90be9c0635

Source dataset

uspto-grants-2011_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08003689B2