Triphenylphosphine → (S)-Tert-butyl 2-(((5-bromopyridin-3-YL)oxy)methyl)azetidine-1-carboxylate

Participants

Reaction Steps

Triphenylphosphine (4.01 g, 15.3 mmol) and DEAD (2.43 mL, 15.3 mmol) were dissolved in 30 mL of THF at 0° C., and the mixture was stirred for 10 minutes. Samples of 1-t-butyloxycarbonyl-2-(S)-azetidinemethanol (2.86 g, 15.3 mmol, Step 7c above) and 3-bromo-5-hydroxypyridine.(1.51 g, 10.2 mmol, Step 10c above) were added, and the mixture was stirred for 40 hours at room temperature. The volatile components were removed under vacuum, and the residue was triturated with hexane. The separated hexane fraction was concentrated, and the residue was chromatographed (silica gel; hexane/ether, 10:1 to 10:2) to afford 5-bromo-3-((1-t-butyloxycarbonyl-(2S)-azetidinyl)methoxy)pyridine as a colorless oil (1.669 g): 1H NMR (CDCl3, 300 MHz) δ1.42 (s, 9H), 2.31 (m, 2H), 3.89 (m, 2H), 4.12 (m, 1H), 4.322 (m, 1H), 4.52 (m, 1H), 7.43 (m, 1H), 8.29 (m, 2H); MS (CI/NH3) m/z 344 (M+H)+. The 5-bromo-3-(2-(1-BOC-2-(S)-azetidinyl)methoxy)pyridine was treated with with 4 M HCl in dioxane to give the free base of the title compound. This was converted to the dihydrochloride salt and recrystallized from methanol/ether to provide the title compound: mp 163-165° C.; [α]25D −5.1 (c 0.57, methanol); 1H NMR (D2O, 300 MHz) δ8.36 (d, J=1.8 Hz, 1H), 8.32 (d, J=2.6 Hz, 1H), 7.84 (dd, J=1.8, 2.6 Hz, 1H), 4.98-4.90 (m, 1H), 4.43 (d, J=4.0 Hz, 2H), 4.20-4.02 (m, 2H), 2.67 (q, J=8.5 Hz, 2H); MS (CI/NH3) m/z 243/246 (M+H)+, 260/262 (M+NH4)+. Anal. calcd for C9H13N2OBrCl2: C, 34.21; H, 4.15; N, 8.86. Found: C, 34.18; H, 4.17; N, 8.89.

Provenance & Evidence