Triphenylphosphine → HCID 86679978, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-azido-1-(1-methyl-4-nitro-1H-pyrazol-5-yl)azepan-3-ol, Intermediate 18 (3.4 g, 16 mmol) in THF (40 mL) and water (8 mL), was added triphenylphosphine (1.89 g, 7.2 mmol) and the mixture was heated at 65° C. for 16 hr. The solvents were removed under reduced pressure to afford 5-amino-1-(1-methyl-4-nitro-1H-pyrazol-5-yl)azepan-3-ol (contaminated with triphenylphosphine oxide) as a viscous oil. To this amine in DCM (40 mL), di-tert-butyl dicarbonate (4.49 g, 20.6 mmol) and DIPEA (4.78 mL, 27.4 mmol) were added and the mixture stirred at room temperature for 60 hr. The solvent was removed under reduced pressure and the residue purified by silica gel column chromatography (0-100% EtOAc/isohexane) to give tert-butyl 6-hydroxy-1-(1-methyl-4-nitro-1H-pyrazol-5-yl)azepan-4-ylcarbamate as a yellow oil (2.6 g). To a solution of this oil (2.6 g, 10.2 mmol) in DCM (50 mL) was added deoxo-Fluor® (50% in THF, 6.7 mL, 18.6 mmol) and the mixture was stirred at room temperature for 16 hr. The mixture was diluted with DCM (30 mL), cooled in an ice/water bath and quenched by the dropwise addition of saturated aqueous NaHCO3 (30 mL). The resulting mixture was stirred for 10 min. The organic layer was separated, dried over Na2SO4 and the solvent removed under reduced pressure. Purification via silica gel column chromatography (0-50% EtOAc/isohexane) gave tert-butyl 6-fluoro-1-(1-methyl-4-nitro-1H-pyrazol-5-yl)azepan-4-ylcarbamate (1.07 g, 66% over three steps) as a pale yellow oil. 1H NMR (400 MHz, CDCl3) δ 8.14-7.97 (m, 1H), 5.04-4.46 (m, 3H), 3.96-2.99 (m, 6H), 2.42-1.64 (m, 5H), 1.70-1.22 (m, 9H).

Provenance & Evidence