Sodium Azide → 3-azido-2,3-dimethyl-6-(1-methyl-4-nitro-1H-pyrazol-5-yl)dihydro-2H-pyran-4(3H)-one

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-(5,6-dimethyl-4-((triethylsilyl)oxy)-3,6-dihydro-2H-pyran-2-yl)-1-methyl-4-nitro-1H-pyrazole (507 mg, 1.38 mmol, intermediate 85) in dry MeCN (3.5 mL) cooled to −20° C. was added sodium azide (404 mg, 6.22 mmol) followed by a solution of cerium ammonium nitrate (2.27 g, 4.15 mmol) in CH3CN (10.4 mL) dropwise. The reaction mixture was stirred at −20° C. for 1 hr, slowly warmed to 0° C. over 1 hr then quenched with water (20 mL) and extracted with EtOAc (20 mL). The organic layer was washed with water (10 mL) and brine (10 mL), separated, dried over Na2SO4 and concentrated under reduced pressure. Purification via silica gel column chromatography (0-100% EtOAc/isohexane) gave 3-azido-2,3-dimethyl-6-(1-methyl-4-nitro-1H-pyrazol-5-yl)dihydro-2H-pyran-4(3H)-one as a white solid (187 mg, 46%). 1H NMR (400 MHz, CDCl3) δ 8.05 (s, 1H), 5.78 (dd, J=12.3, 3.2 Hz, 1H), 4.21 (s, 3H), 3.73 (dd, J=12.3, 6.2 Hz, 1H), 3.13 (dd, J=14.6, 12.3 Hz, 1H), 2.73 (dd, J=14.6, 3.2 Hz, 1H), 1.44 (s, 3H), 1.41 (d, J=6.1 Hz, 3H).

Provenance & Evidence