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.
A new synthesis of novel alkenylated flavones by palladium-catalyzed cross-coupling reactions
作者:Szabolcs Fekete、Tamás Patonay、Artur M. S. Silva、José A. S. Cavaleiro
DOI:10.3998/ark.5550190.0013.519
日期:——
Bromoflavones were treated with various terminal alkynes in palladium-catalyzedcross-couplingreactions under phosphine-free condions to give the expected alkenylatedflavones in moderate to good yields. The presence of two differenthydrogens in the terminal alkene led to the formation of both alkenylated and alkylated products.