Triethyl phosphonoacetate → 3-Ethoxycarbonylmethylene-9-aza-bicyclo[3.3.1]nonane-9-carboxylic acid tert-butyl ester

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Reaction Steps

0.54 ml of (diethoxy-phosphoryl)-acetic acid ethyl ester are added dropwise to a suspension of 108 mg of NaH (55% in mineral oil) in 5 ml of THF at 0°. The mixture obtained is stirred and 650 mg of 3-oxo-9-aza-bicyclo[3.3.1]nonane-9-carboxylic acid tert-butyl ester in 5 ml of THF are slowly added. The mixture obtained is stirred at 60° C. for 3 days, diluted with c-HEX and washed with 1M aqueous NaH2PO4 and saturated aqueous NaHCO3 solution. The organic layer obtained is dried, solvent is evaporated and the evaporation residue obtained is subjected to chromatography on silica gel. 3-Ethoxycarbonylmethylene-9-aza-bicyclo[3.3.1]nonane-9-carboxylic acid tert-butyl ester is obtained in the form of an oil. 13C-NMR: 171.79, 154.45, 154.27, 133.38, 132.77, 127.11, 126.30, 79.64, 79.54, 61.03, 61.00, 48.59, 47.20, 46.81, 45.22, 42.72, 33.61, 33.42, 32.59, 32.17, 30.73, 30.07, 28.87, 28.57, 28.13, 16.48, 14.59.

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