developed. 1-(2-Hydroxyphenyl)-3-phenylpropane-1,3-diones were fluorinated using selectfluor with a small amount of CH3CN at room temperature, followed by cyclization and dehydration in the presence of a trace amount of conc. H2SO4 to provide 3-fluoroflavones. The desired 3-fluoroflavone analogues were obtained in moderate to excellent yields. This strategy tolerated a wide range of functional groups and
开发了一种简洁高效的一锅法合成3-氟黄酮。在室温下,使用带有少量CH 3 CN的selectfluor对1-(2-羟基苯基)-3-苯基丙烷-1,3-二酮进行氟化,然后在痕量浓盐酸存在下进行环化和脱水。H 2 SO 4提供3-氟黄酮。以中等至优异的产率获得了所需的3-氟黄酮类似物。该策略可耐受各种官能团,不需要复杂的仪器或繁琐的底物制备。
A New Synthesis of 5-Arylbenzo[c]xanthones from Photoinduced Electrocyclisation and Oxidation of (E)-3-Styrylflavones
A new synthetic route to 5-arylbenzo[c]xanthones is established. This was accomplished by use the Heck reaction of 3-bromoflavones with styrene derivatives, leading to (E)-3-styrylflavones with total diastereoselectivity. This transformation was greatly improved under microwave irradiation. The one-pot, photoinduced electrocyclisation of (E)-3-styrylflavones and further in situ oxidation of the cycloadduct leads to 5-arylbenzo[c]xanthones.