反应详情

To a stirred, cooled (−50° C.) solution of 643 mg(2.8 mmol) of 5-(t-butoxycarbonylamino)-2-chloropyridine in 8 mL of anhydrous THF was added 4.7 mL(7.9 mmol) of t-BuLi in pentane over 3 min. The solution was stirred an additional 35 min. at −50° C. after which time 1 mL(large excess) of 4-cyclopropyl-1,1,1-trifluoro-3-butyn-2-one. The solution was stirred an additional 20 min., warming to ambient temperature. The reaction was poured into 10% aq. citric acid, and the mixture was extracted with 1:1 ether-ethyl acetate. The organic extract was washed with saturated aq. NaHCO3, then brine, dried (MgSO4), and concentrated under reduced pressure. Chromatography on silica gel(gradient elution with 6:1 then 3:1 hexanes-ethyl acetate) afforded, after removal of solvent, 620 mg(56%) of 2-(5-(t-butoxycarbonylamino)-2-chloropyrid-4-yl)-4-cyclopropyl-1,1,1-trifluoro-3-butyn-2-ol as an amorphous solid. Mass spec.(NH3—CI): 391((M+H)+, 100%); 291((M+H-t-Boc)+, 49%). 1H NMR(300 MHz, CDCl3) δ 9.08(br. s, 1H); 8.29(br. s, 1H); 7.59(s, 1H); 1.50(s, 9H); 1.37-1.43(m, 1H); 0.81-0.97(m, 4H).

1. extractionthe mixture was extracted with 1:1 ether-ethyl acetate
2. extractionThe organic extract
3. washwas washed with saturated aq. NaHCO3
4. dry with materialbrine, dried (MgSO4)
5. concentrationconcentrated under reduced pressure
6. washChromatography on silica gel(gradient elution with 6:1
7. custom3:1 hexanes-ethyl acetate) afforded
8. customafter removal of solvent, 620 mg(56%) of 2-(5-(t-butoxycarbonylamino)-2-chloropyrid-4-yl)-4-cyclopropyl-1,1,1-trifluoro-3-butyn-2-ol as an amorphous solid