Novel and facile synthesis of β-(4-azuleno[1,2-b]thienyl)- and β-(4-azuleno[2,1-b]thienyl)-α,β-unsaturated ketones by intramolecular tropylium ion-mediated furan ring-opening reaction
The novel and efficient methods for the synthesis of β-(4-azuleno[1,2-b]thienyl)-α,β-unsaturatedketones (1) and β-(4-azuleno[2,1-b]thienyl)-α,β-unsaturatedketones (2) have been described. Refluxing the dichloromethane solutions of 2-tropylio-3-(2-furyl)thiophene tetrafluoroborates (3) or 3-tropylio-2-(2-furyl)thiophene tetrafluoroborates (4) afforded (1) and (2), respectively, in moderate yields
合成β-(4-azuleno [1,2- b ]噻吩基)-α,β-不饱和酮(1)和β-(4-azuleno [2,1- b ]噻吩基)的新颖有效方法已经描述了-α,β-不饱和酮(2)。回流2-对甲苯基-3-(2-呋喃基)噻吩四氟硼酸酯(3)或3-对甲苯基-2-(2-呋喃基)噻吩四氟硼酸酯(4)的二氯甲烷溶液,分别得到(1)和(2)。中等产量。该反应涉及分子内的yl离子介导的呋喃开环反应。
Novel and efficient one-pot synthesis of azuleno[1,2-<i>b</i>]-benzothiophenic enones from the corresponding 2-cycloheptatrientyl-3-(2-furyl)benzothiophenes
2-Cycloheptatrienyl-3-(2-furyl)benzothiophenes, which are prepared by Stille coupling reaction of 2-cyclo-heptatrienyl-3-bromobenzothiophene with the 5-substituted 2-trimethylstannylfurans, react with triphenylmethyl tetrafluoroborate to give the correspondingazuleno[1,2-b]benzothiophenic enones in excellent yields.