Ethanol → (E)-ethyl 2-methyl-7-phenylhept-2-enoate

Participants

Reaction Conditions

Reaction Steps

Triethyl-2-phosphonopropionate (12 g, 50 mmol) and 5-phenylpentanal (7 g, 43 mmol) are dissolved in dry THF (100 mL) and cooled to 10° C. A solution of sodium ethoxide in ethanol (23 mL, 21%, 43 mmol) is added slowly over 20 minutes and the reaction is warmed to 23° C. After stirring 1 hour, the reaction is quenched by the addition of a saturated NH4Cl solution (30 mL). The reaction is concentrated to remove the THF in vacuo, diluted with petroleum ether (400 mL) and washed with 1 N HCl (100 mL), H2O (100 mL), NaHCO3 (100 mL), brine (100 mL) and dried (MgSO4). The solution is concentrated in vacuo and purified by filtration through a plug of silica gel using 2% ether/pet ether as the eluant to yield (E)-ethyl 2-methyl-7-phenylhept-2-enoate, (8.9 g, 84%) which contains a small amount (10%) of the Z-isomer: 1H NMR (CDCl3) δ 7.29-7.23 (m, 2H), 7.19-7.14 (m, 3H), 6.75 (dt, J=15.5, 1.5 Hz, 1H), 4.18 (q, J=7.1 Hz, 2H), 2.62 (t, J=7.5 Hz, 2H), 2.18 (q, J=7.0 Hz, 2H), 1.81 (s, 3H), 1.70-1.59 (m, 2H), 1.54-1.42 (m. 2H), 1.28 (t, J=7.1 Hz, 3H); MS (FAB) m/e 247 (M+H)+.

Provenance & Evidence