Regioselective bromination and fluorination of apogossypol hexamethyl ether
摘要:
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% yield. When treated with bromine and iron powder in CCl4 at-5-degrees-C, 3 afforded 5 in 65% yield. The reaction of 3 with pyridinium bromide perbromide in 1,2-dichloroethane at 65-70-degrees-C furnished 6 in 70% yield. Treatment of 3 with NBS in DMF at room temperature afforded 7 in 30% 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(1) fluoride.
Regioselective bromination and fluorination of apogossypol hexamethyl ether
作者:Guidong Zhu、Dehua Chen、Jianhua Huang、Chingsung Chi、Fukuang Liu
DOI:10.1021/jo00034a024
日期:1992.4
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% yield. When treated with bromine and iron powder in CCl4 at-5-degrees-C, 3 afforded 5 in 65% yield. The reaction of 3 with pyridinium bromide perbromide in 1,2-dichloroethane at 65-70-degrees-C furnished 6 in 70% yield. Treatment of 3 with NBS in DMF at room temperature afforded 7 in 30% 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(1) fluoride.