Water → N-[(4aR,6R,8aS)-6-[(benzyloxy)methyl]-8a-(2,4-difluorophenyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide

Participants

Reaction Conditions

Reaction Steps

Pyridine (11.0 mL, 137 mmol) was added to a solution of N-{[(3S,4R,6R)-6-[(benzyloxy)methyl]-3-(2,4-difluorophenyl)-4-(hydroxymethyl)tetrahydro-2H-pyran-3-yl]carbamothioyl}benzamide (C7) (19.00 g, 36.08 mmol) in dichloromethane (150 mL), and the resulting solution was cooled to −50 to −60° C. Trifluoromethanesulfonic anhydride (12.1 mL, 71.9 mmol) in dichloromethane (50 mL) was added drop-wise, and the reaction mixture was gradually warmed to −5° C. over 3 hours. Water was added, and the aqueous layer was extracted with dichloromethane. The combined organic layers were washed with saturated aqueous sodium chloride solution, dried over magnesium sulfate, filtered, and concentrated in vacuo. Purification via silica gel chromatography (Gradient: 20% to 40% ethyl acetate in heptane) provided the product as a yellow foam. Yield: 15.51 g, 30.50 mmol, 85%. LCMS m/z 509.2 [M+H+]. 1H NMR (400 MHz, CDCl3) δ 8.23 (br d, J=7 Hz, 2H), 7.37-7.57 (br m, 4H), 7.24-7.36 (m, 5H), 6.85-6.97 (m, 2H), 4.58 (AB quartet, upfield signals are slightly broadened, JAB=11.9 Hz, ΔνAB=23.5 Hz, 2H), 4.17 (br d, J=12 Hz, 1H), 3.90-3.97 (m, 1H), 3.83 (br d, J=12 Hz, 1H), 3.64 (dd, half of ABX pattern, J=10.1, 6.4 Hz, 1H), 3.50 (dd, half of ABX pattern, J=10.2, 4.4 Hz, 1H), 3.11-3.21 (br m, 1H), 3.02 (dd, J=12.9, 4.1 Hz, 1H), 2.64 (br d, J=13 Hz, 1H), 1.92-2.05 (br m, 1H), 1.71 (br d, J=13 Hz, 1H).

Provenance & Evidence