Imidazole → [(3S,6R)-6-(tert-butyl-dimethyl-silanyloxy)-2-oxo-azepan-3-yl]-carbamic acid tert-butyl ester

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Reaction Steps

To a stirred solution of (3S, 6R)-3-(tert-butoxycarbonyl)aminohexahydro-6-hydroxy-2H-azepin-2-one (25 g, 102 mmol) in DMF (60 mL) is added tert-butyldimethylsilyl chloride (23.16 g, 153 mmol), and imidazole (10.45 g, 153 mmol). The reaction is stirred at room temperature for 18 h, diluted with 1 L of water and extracted with a 1:1 (2×200 mL) mixture of ethyl acetate and hexane. All organic layers are combined, washed with brine, dried with NaSO4, and concentrated under vacuum. The residue is purified by recrystallization with ethyl acetate/hexane to give 28.5 g (78%) of (3S, 6R)-3-(tert-butoxycarbonyl) aminohexahydro-6-tert-butyldimethylsilyloxy-2H-azepin-2-one as a white solid, melting point: 65-66° C.; 1H NMR (CDCl3) δ 5.86 (d, J=6 Hz, 1H), 5.58 (t, J=6 Hz, 1H), 4.18 (m, 1H), 3.91 (s, 1H), 3.35(dd, J=6 Hz and 16 Hz, 1H), 3.07 (m, 1H), 1.80 (m, 4H), 1.40 (s, 9H), 0.83 (s, 9H), 0.004 (s, 6H).

Provenance & Evidence