Thionyl Chloride → [(S)-2-(7-Azidomethyl-furo[2,3-g]indazol-1-yl)-1-methylethyl]-carbamic acid benzyl ester

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Reaction Steps

A suspension of the product from Example 3, Step B (2.80 g, 7.39 mmol) in dichloromethane (30 mL) was cooled (ice bath), thionyl chloride (0.81 mL, 11.1 mmol) was added and the mixture was stirred for 30 minutes. During the reaction the white suspension dissolved to a yellow solution and then became a white suspension. The reaction was evaporated. The residue was treated with a solution of sodium azide (5 eq, 37 mmol, 2.4 g) in DMSO (40 mL, heated at 70° C. to dissolve) with stirring and let cool to room temperature for 20 minutes. The reaction was quenched with saturated aqueous sodium bicarbonate (100 mL) and extracted with dichloromethane (200 mL). The organic layer was washed with brine (100 mL), dried (MgSO4) and evaporated to give a yellow oil, 2.84 g. This residue was purified by chromatography (silica gel, hexane/ethyl acetate gradient) to give a colorless waxy residue, 2.45 g (82%) LC/MS m/z 405 [M+H]+.

Provenance & Evidence