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(1R,3S)-(+)-cis-4-cyclopentene-1,3-diol 1-acetate (3-1) (500 mg, 3.5 mmol, 1.0 equiv) was dissolved in dry THF (17.6 mL). Triphenylphosphine (1.4 g, 5.3 mmol, 1.5 equiv) was added, followed by 4,7-difluoro-1H-imidazo[4,5-c]pyridine (1-4) (655 mg, 4.2 mmol, 1.2 equiv). The mixture was cooled to 0° C. and DIAD (1 mL, 5.3 mmol, 1.5 equiv) was added dropwise. The resulting mixture was stirred at ambient temperature for 1 hour. Upon disappearance of starting material, the solvent was removed at reduced pressure and the yellow residue was purified via flash chromatography on a 120 g silica gel column (gradient elution 0 to 100% ethyl acetate in hexanes) to yield (1R,4R)-4-(4,7-difluoro-1H-imidazo[4,5-c]pyridin-1-yl)cyclopent-2-enyl acetate (4-1) and (1R,4R)-4-(4,7-difluoro-3H-imidazo[4,5-c]pyridin-3-yl)cyclopent-2-enyl acetate (4-2) as a 2:3 regioisomeric mixture. 1H NMR (4-1) (500 MHz, CDCl3): δ 7.907 (s, 1H); 7.83 (t, J=2.5 Hz, 1H); 6.44 (m, 1H); 6.31 (m, 1H); 5.93-5.99 (m, 2H); 2.67 (m, 1H); 2.43 (m, 1H); 2.10 (s, 3H). LRMS m/z (M+H) 279.9 found, 280.1 required. 1H NMR (4-2) (500 MHz, CDCl3): δ 7.98 (s, 1H); 7.81 (t, J=2 Hz, 1H); 6.44 (m, 1H); 6.31 (m, 1H); 5.93-5.99 (m, 2H); 2.67 (m, 1H); 2.43 (m, 1H); 2.10 (s, 3H). LRMS m/z (M+H) 279.9 found, 280.1 required.

1. customUpon disappearance of starting material, the solvent was removed at reduced pressure
2. customthe yellow residue was purified via flash chromatography on a 120 g silica gel column (gradient elution 0 to 100% ethyl acetate in hexanes)