Diisopropylethylamine → HCID 89525258, compound

Temperature

110 °C

(R)—N—Boc-pyrrolidine-3-carboxylic acid (700 mg, 3.25 mmol, 1.1 equiv), HBTU (1.23 g, 1.1 equiv) and DIEA (1.53 mL, 3 equiv) were dissolved in DMF (15 mL). The solution was stirred 5 min and then 1,3-thiazole-2-amidoxime (5a) (422 mg, 2.95 mmol, 1 equiv) was added. The reaction mixture was stirred overnight at room temperature and then evaporated under reduced pressure. The residue was dissolved in AcOEt, washed twice with saturated aqueous NaHCO3, once with brine, then dried over MgSO4 and evaporated under reduced pressure. The residue was dissolved in 15 mL of DMF and then heated at 110° C. for 7 h. The solvent was removed under vacuum and the residue was dissolved in AcOEt. The organic layer was washed once with HCl 1N, once with saturated aqueous NaHCO3 and once with brine, then dried over MgSO4 and evaporated under reduced pressure. The obtained product was used in the next step without further purification. Boc intermediate was dissolved in dioxane (10 mL) and HCl 4N solution in dioxane (6 mL) was added. The reaction mixture was stirred overnight at room temperature and then the product was recovered by filtration and washed with petroleum ether to give 5-[(3R)-pyrrolidin-3-yl]-3-(1,3-thiazol-2-yl)-1,2,4-oxadiazole (yield 66% over two steps). 4,4,4-trifluorobutyric acid (1.3 equiv), EDCI (1.3 equiv), HOBt (0.4 equiv) and DIEA (4 equiv) were mixed in DMF (2 mL) for 5 minutes. 5-[(3R)-pyrrolidin-3-yl]-3-(1,3-thiazol-2-yl)-1,2,4-oxadiazole (0.62 mmol, 1 equiv) was added with 3 mL of DMF. The reaction mixture was stirred overnight at room temperature and then evaporated under reduced pressure and purified by preparative HPLC. Beige powder; Yield 33%; 1H NMR (CDCl3) δ 8.02-8.00 (m, 1H), 7.57-7.60 (m, 1H), 3.89-4.03 (m, 2H), 3.69-3.87 (m, 2H), 3.53-3.65 (m, 1H), 2.38-2.55 (m, 6H); 13C NMR (CDCl3) cis/trans isomer mixture (60 isomer A/40 isomer B); isomer A δ 180.31, 168.50, 163.98, 153.53, 144.99, 126.94 (q, J=276 Hz), 122.87, 49.24, 45.52, 35.03, 29.05 (q, J=29 Hz), 28.86, 27.07 (q, J=3 Hz); isomer B δ 179.84, 168.31, 163.98, 153.38, 144.94, 126.92 (q, J=276 Hz), 122.81, 49.43, 45.25, 36.82, 30.28, 29.05 (q, J=29 Hz), 27.24 (q, J=3 Hz). tR LCMS 4.6 min. Purity >99%; MS [M+H]+ m/z 347.

1. stirringThe reaction mixture was stirred overnight at room temperature
2. customevaporated under reduced pressure
3. dissolutionThe residue was dissolved in AcOEt
4. washwashed twice with saturated aqueous NaHCO3, once with brine
5. dry with materialdried over MgSO4
6. customevaporated under reduced pressure
7. dissolutionThe residue was dissolved in 15 mL of DMF
8. customThe solvent was removed under vacuum
9. dissolutionthe residue was dissolved in AcOEt
10. washThe organic layer was washed once with HCl 1N, once with saturated aqueous NaHCO3 and once with brine
11. dry with materialdried over MgSO4
12. customevaporated under reduced pressure
13. customThe obtained product was used in the next step without further purification
14. dissolutionBoc intermediate was dissolved in dioxane (10 mL)
15. additionHCl 4N solution in dioxane (6 mL) was added
16. stirringThe reaction mixture was stirred overnight at room temperature
17. filtrationthe product was recovered by filtration
18. washwashed with petroleum ether

ORD record

ord-6df2cf6966e941a49e61aaf9a3f8a1bc

Source dataset

uspto-grants-2015_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08962658B2