Boron trifluoride etherate → HCID 67034856, compound

Participants

Reaction Conditions

Reaction Steps

1st method: A solution A is prepared from 500 mg of the compound of the above Step, 6-bromo-1-(2-hydroxy-4,5-dimethoxyphenyl)-hexan-1-one (1.5 mmol), dissolved in 0.60 ml (4.5 mmol) of Et2O—BF3, and the solution is cooled to 10° C. 2.3 ml of DMF are then added. There is prepared, in addition, a solution B of 4 ml of DMF and there is added thereto in small portions at 10° C. 470 mg (2.25 mmol) of PCl5. Solution B is heated at 55° C. for 20 min, and is then introduced dropwise into solution A, referred to at the beginning, with a return to ambient temperature. The mixture turns orangey yellow and precipitates. 50 ml of 0.1N HCl are introduced and the mixture is extracted with AcOEt, the organic phases are washed with saturated NaCl solution, separated, dried over MgSO4, filtered and evaporated. The residue is subjected to flash chromatography over SiO2 with a gradient of pure heptane to heptane-AcOEt 70-30. The purified fractions crystallise after evaporation. 300 mg of 3-(4-bromobutyl)-6,7-dimethoxychromen-4-one are obtained in the form of crystals (yield=59%); TLC SiO2hept-AcOEt 50-50 Rf=0.4.

Provenance & Evidence