Regioselective Bromination and Fluorination of Apogossypol Hexamethyl Ether

Article abstract of DOI:10.1021/jo00034a024

Apogossypol hexamethyl ether (3) was brominated upon treatment with any of a number of brominating agents.Each reagent gave a different bromo derivative.Thus, the reaction of 3 with bromine in CCl4 with ultrasound irradiation gave 4 in 71 percent yield.When treated with bromine and iron powder in CCl4 at -5 deg C, 3 afforded 5 in 65 percent yield.The reaction of 3 with pyridinium bromide perbromide in 1,2-dichloroethane at 65-70 deg C furnished 6 in 70 percent yield.Treatment of 3 with NBS in DMF at room temperature afforded 7 in 30 percent yield.Treatment of 4 and 5 with potassium fluoride and 18-crown-6 in acetonitrile at room temperature furnished 8 and 9, respectively.An attempt to introduce trifluoromethyl groups at the 8 and 8' positions of 4, by treatment with cuprous iodide and sodium trifluoroacetate, failed and gave only 10.Interestingly, but unexpectedly, 11 and 12 were produced upon treating 4 with silver(I) fluoride.