p-Toluenesulfonic acid → 7-Bromo-6-[3-bromo-2-(1-ethoxyethoxy)-propoxy]-1-[2-(tert-butyldimethyl-silanyloxy)-propyl]-1H-indazole

Participants

Reaction Steps

To a solution of the product from Step E (3.78 g, 7.2 mmol) and p-toluenesulfonic acid (0.14 g) in dichloromethane (50 mL) at 0° C. was added ethyl vinyl ether (2.75 mL, 28.8 mmol). After 30 min the reaction was quenched with a saturated solution of sodium bicarbonate (50 mL) and the mixture was extracted with dichloromethane (3×80 mL). Evaporation and purification by chromatography (silica, 1% to 8% EtOAc/hexane) gave a viscous oil (3.30 g, 77%): LC/MS (+APCI) m/z 593, 595, 597 (M+H).

Provenance & Evidence