Azidotrimethylsilane → HCID 89456912, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of (2E,6Z)-3-(1-methyl-4-nitro-1H-pyrazol-5-yl)cyclohepta-2,6-dienone (690 mg, 2.95 mmol) in acetonitrile (10 mL) was added trimethylsilyl azide (1 mL, 7.57 mmol) and Amberlite™ IRA900F resin (590 mg, 1.47 mmol). The reaction mixture was stirred at 40° C. for 5 hr, cooled to room temperature, filtered and concentrated under reduced pressure to give (E)-6-azido-3-(1-methyl-4-nitro-1H-pyrazol-5-yl)cyclohept-2-enone as a yellow oil. To a solution of this oil (810 mg, 2.93 mmol) in THF (20 mL) and water (6 mL) was added sodium borohydride (166 mg, 4.40 mmol). The mixture was stirred at room temperature for 18 hr before being diluted with water (50 mL). The mixture was extracted with EtOAc (100 mL) and the organic layer was separated, dried over MgSO4 and concentrated under reduced pressure. Purification via silica gel column chromatography (0-100% EtOAc/isohexane) gave (E)-6-azido-3-(1-methyl-4-nitro-1H-pyrazol-5-yl)cyclohept-2-enol as a yellow oil. This oil (810 mg, 2.91 mmol) was dissolved in THF (15 mL) and added to a suspension of polymer-supported triphenylphosphine (3.1 g, 5.76 mmol) in THF (45 mL) and water (1.5 mL). The mixture was gently stirred at 60° C. for 18 hr, cooled to room temperature and concentrated under reduced pressure. The residue was diluted in DCM (30 mL) and di-tert-butyl dicarbonate (754 mg, 3.46 mmol) and DIPEA (1.51 mL, 8.64 mmol) were added. The mixture was stirred at room temperature for 5 hr, diluted with DCM (50 mL) and quenched with a saturated solution of sodium hydrogencarbonate (50 mL). The organic layer was washed with water (50 mL), separated, dried over MgSO4 and concentrated under reduced pressure. Purification via silica gel column chromatography (0-100% EtOAc/isohexane) gave (E)-tert-butyl 5-(1-methyl-4-nitro-1H-pyrazol-5-yl)-3-oxocyclohept-4-enylcarbamate as a white foam (620 mg, 59% over three steps). 1H NMR (400 MHz, CDCl3) δ 8.05 (s, 1H), 6.03-5.99 (m, 1H), 4.82-4.60 (m, 2H), 3.86-3.82 (m, 4H), 2.82-2.34 (m, 1H), 2.29-2.35 (m, 1H), 2.34-2.20 (m, 2H), 2.15-2.04 (m, 1H), 1.85-1.51 (m, 2H), 1.45 (s, 9H).

Provenance & Evidence