1,8-Diazabicyclo(5.4.0)undec-7-ene → Methyl 2-(5-chloro-2-((2-(trimethylsilyl)ethoxy)methyl)-2H-indazol-7-yl)-2-diazoacetate

Participants

Reaction Steps

To a solution of methyl 2-(5-chloro-2-((2-(trimethylsilyl)ethoxy)methyl)-2H-indazol-7-yl)acetate (1.95 g, 5.49 mmol) and 4-acetamidobenzenesulfonyl azide (1.52 g, 6.32 mmol) in acetonitrile (11 mL) at 0° C. was added 1,8-Diazabicyclo[5.4.0]undec-7-ene (1.04 mL, 6.87 mmol) dropwise over 20 min. The ice bath was removed and stirring continued at room temperature for 1 h. The reaction was partitioned between water and ethyl acetate. The organics were washed with saturated sodium bicarbonate, dried over sodium sulfate, and concentrated. The resulting residue was purified by column chromatography (8%→25% ethyl acetate/n-hexane) to give 1.39 g (66%) as a yellow oil. 1H-NMR (CDC13, 500 MHz) δ 8.01 (s, 1H), 7.79 (d, J=1.5 Hz, 1H), 7.45 (d, J=1.8 Hz, 1H), 5.64 (s, 2H), 3.89 (s, 3H), 3.64 (t, J=8.2 Hz, 2H), 0.93 (t, J=8.4 Hz, 2H), −0.03 (s,9H; 13C NMR (126 MHz, CDCl3) δ ppm 165.9, 143.2, 128.7, 125.3, 123.1, 122.7, 122.5, 116.5, 116.4, 81.8, 67.9, 52.1, 17.8, −1.4.

Provenance & Evidence