Triethyl phosphonoacetate → HCID 117697698, compound

Participants

Reaction Steps

To a suspension of sodium hydride (396 mg, 60% dispersion in mineral oil, 9.9 mmol) in dry THF (5 ml) was added 2-diethoxyphosphorylacetic acid ethyl ester (2.40 g, 10.8 mmol) at 0° C. The resulting mixture was stirred at room temperature for 10 mins, and then heated at 80° C. for 20 mins. The reaction mixture was cooled down to room temperature. To the reaction mixture was added a solution of tert-butyl 7-oxo-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate (2.00 g, 8.3 mmol) in dry THF (20 ml). The resulting mixture was stirred at 80° C. overnight. The solvent was removed and the residue was partitioned between ethyl acetate and water. The organic phase was dried, concentrated and purified by silica gel chromatography to give tert-butyl 7-(2-ethoxy-2-oxo-ethylidene)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate 123b (1.20 g, 46.5%) and tert-butyl 7-(2-ethoxy-2-oxo-ethyl)-3-oxa-9-azabicyclo[3.3.1]non-6-ene-9-carboxylate 123e (0.800 g, 30.8%). Compound 123b: 1H NMR (400 MHz, CDCl3): d=5.72-5.66 (m, 1H), 4.29-4.23 (m, 1H), 4.15 (d, J=7.3 Hz, 3H), 4.05-3.97 (m, 1H), 3.88-3.77 (m, 2H), 3.76-3.65 (m, 2H), 2.77-2.61 (m, 1H), 2.38 (d, J=15.3 Hz, 2H), 1.53-1.48 (m, 9H), 1.30-1.26 (m, 3H).

Provenance & Evidence