反応手順
(3aS,4S,6S,6aR)-2,2,6-trimethyltetrahydro-3aH-cyclopenta[d][1,3]dioxol-4-ol (6-2) (400 mg, 2.3 mmol, 1 equiv) was dissolved in THF (25 mL). Triphenylphosphine (914 mg, 3.5 mmol, 1.5 equiv) was added followed by 4,7-difluoro-1H-imidazo[4,5-c]pyridine (1-4) (396 mg, 2.6 mmol, 1.1 equiv). The mixture was cooled to 0° C. and DIAD (0.72 mL, 3.7 mmol, 1.6 equiv) was added dropwise. The resulting mixture was stirred at ambient temperature for 14 hours and then heated to 50° C. for an additional 72 hours. The solvent was removed at reduced pressure and the yellow residue was purified via flash chromatography (40 g SiO2, 15-100% EtOAc in hexanes) to yield 4,7-difluoro-1-((3aS,4R,6S,6aR)-2,2,6-trimethyltetrahydro-3aH-cyclopenta[d][1,3]dioxol-4-yl)-1H-imidazo[4,5-c]pyridine (6-3) and 4,7-difluoro-3-((3aS,4R,6S,6aR)-2,2,6-trimethyltetrahydro-3aH-cyclopenta[d][1,3]dioxol-4-yl)-3H-imidazo[4,5-c]pyridine (6-4) as a 1:1 regioisomeric mixture. 1H NMR (6-3) (500 MHz, CDCl3): δ 8.02 (s, 1 H); 7.84 (t, J=4.5 Hz, 1H); 4.80-4.91 (m, 2H); 4.41 (q, J=6.5 Hz, 1H); 2.53 (sextuplet, J=6.5 Hz, 1H); 2.29 (septuplet, J=6.0 Hz, 1H); 2.00 (m, 1H); 1.57 (s, 3H); 1.31 (s, 3H); 1.25 (d, J=6.5 Hz, 3H). LRMS m/z (M+H) 309.9 found, 310.1 required. 1H NMR (6-4) (500 MHz, CDCl3): δ 8.10 (s, 1H); 7.81 (t, J=5.0 Hz, 1H); 4.80-4.91 (m, 2H); 4.41 (q, J=6.5 Hz, 1H); 2.53 (sextuplet, J=6.5 Hz, 1H); 2.29 (septuplet, J=6.0 Hz, 1H); 2.00 (m, 1H); 1.57 (s, 3H); 1.31 (s, 3H); 1.25 (d, J=6.5 Hz, 3H). LRMS m/z (M+H) 309.9 found, 310.1 required.
