Benzamide → N-[(3S,4R)-3-Hydroxy-2,2-dimethyl-6-(trifluoromethoxy)-chroman-4-yl]-4-chloro-2-nitrobenzamide

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Reaction Steps

4-Chloro-2-nitrobenzoic acid (2.02 g, 10 mmol) was converted to the corresponding acid chloride by refluxing in benzene (30 mL) with thionyl chloride (2.38 g, 20 mmol) for 2 hours. The crude mixture was concentrated in vacuo and diluted with dichloromethane (10 mL). This solution was added to a cooled solution of (3S,4R)-4-amino-2,2-dimethyl-6-(trifluoromethoxy)-chroman-3-ol (2.75 g, 10 mmol), triethylamine (1.39 mL, 10 mmol) and dichloromethane (25 mL). The crude benzamide was worked-up in a method similar to that in Example 1 and chromatographed (1:1 hexanes/ethyl acetate) to afford 2.0 g (43%) of white solid: m.p. 64°-66° C.; 1H NMR (DMSO-d6): δ 9.24 (d, 1H), 8.19 (s, 1H), 7.96 (d, 1H), 7.83 (d, 1H), 7.29 (s, 1H), 7.18 (d, 1H), 6.86 (d, 1H), 5.88 (d, 1H), 4.94 (br t, 1H), 3.64 (dd, 1H), 1.42 (s, 3H), 1.19 (s, 3H).

Provenance & Evidence