Dimethylformamide → Di-tert-butyl (1S,2R,3R,4S,5R,6S)-4-azido-2-[(tert-butoxycarbonyl)amino]-3-[(3,4-dichlorobenzyl)oxy]bicyclo[3.1.0]hexane-2,6-dicarboxylate

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Reaction Steps

Sodium azide (8.29 g, 127.45 mmol) is added to di-tert-butyl (1S,2R,3S,4R,5R,6R)-2-[(tert-butoxycarbonyl)amino]-3-[(3,4-dichlorobenzyl)oxy]-4-[(methylsulfonyl)oxy]bicyclo[3.1.0]hexane-2,6-dicarboxylate (16.99 g, 25.49 mmol) and 15-crown-5 (508.57 μL, 561.46 mg, 2.55 mmol) in dimethylformamide (254.90 mL, 240.96 g, 3.30 moles) at 85° C. and stirred. After 7 days, the reaction is cooled to room temperature then diluted with water and extracted with ethyl acetate (3×). The combined organics are washed with water, brine, dried over magnesium sulfate, filtered, and concentrated under reduced pressure giving a residue. The residue is purified by flash chromatography eluting 2-60% ethyl acetate in hexanes to yield the title compound (11.2 g, 18.3 mmol, 72%). MS (m/z): 635/637 (M+1).

Provenance & Evidence