2,2,2-Trichloroethyl chloroformate → racemic 3-(4-Chloro-phenyl)-8-aza-bicyclo[3.2.1]oct-2-ene-8-carboxylic acid 2,2,2-trichloro-ethyl ester

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Reaction Steps

Racemic 3-(4-Chloro-phenyl)-8-methyl-8-aza-bicyclo[3.2.1]oct-2-ene (4.98 g, 21.31 mmol) in 1,1,1-trichloroethane (60 mL) was heated at reflux and 2,2,2-trichloroethyl chloroformate (3.23 mL, 23.44 mmol) was added dropwise over 10 minutes. The reaction was refluxed for 3 hours, cooled and concentrated to a clear oil. Silica gel flash chromatography using 5% methanol/chloroform as the eluent yielded racemic 3-(4-Chloro-phenyl)-8-aza-bicyclo[3.2.1]oct-2-ene-8-carboxylic acid 2,2,2-trichloro-ethyl ester (7.77 g, 92.2%) as a clear oil which had the following properties: 1H NMR CDCl3 δ: 7.25 (s, 4H), 6.41 (m, 1H), 4.85 (m, 1H), 4.73 (s, 1H), 4.68-4.76 (m, 2H), 3.12 (d, J=17 Hz, 1H), 2.25 (m, 2H), 2.03 (m, 2H), 1.75 (m, 1H).

Provenance & Evidence