Högermeier Jens, Reissig Hans-Ulrich
Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany.
Chemistry. 2007;13(8):2410-20. doi: 10.1002/chem.200601394.
Alkenyl nonaflates (nonafluorobutanesulfonates) are excellent substrates in a variety of palladium-catalysed coupling reactions. We herein demonstrate that bicyclic nonaflates generated from 8-heterobicyclo[3.2.1]octan-3-one derivatives can be coupled with aryl or alkenyl boronic acids in a very efficient manner. The resulting densely functionalised bicyclic skeletons are highly suitable for further synthetic elaboration. The thermal Suzuki couplings provided the expected products in moderate to good yields. Microwave (MW) irradiation dramatically shortened reaction times and gave superior results. Bisboronic ester 19 was also coupled with bicyclic nonaflates, for example, with 14, and double Suzuki-coupling products, such as 22, were isolated in good yields. We demonstrated the great synthetic potential of aryl-substituted 8-heterobicyclo[3.2.1]octene derivatives, such as 15, by the stereoselective conversion of this compound into highly substituted furanose 31 or substituted pyran derivative 33, which were obtained in short and efficient reaction sequences.
链烯基全氟壬磺酸酯(全氟丁烷磺酸酯)在各种钯催化的偶联反应中都是优良的底物。我们在此证明,由8-杂双环[3.2.1]辛-3-酮衍生物生成的双环全氟壬磺酸酯能够以非常有效的方式与芳基或链烯基硼酸偶联。所得的高度官能化的双环骨架非常适合进一步的合成修饰。热条件下的铃木偶联反应以中等至良好的产率得到了预期产物。微波(MW)辐射显著缩短了反应时间并给出了更好的结果。双硼酸酯19也与双环全氟壬磺酸酯偶联,例如与14偶联,并且以良好的产率分离得到了双铃木偶联产物,如22。我们通过将化合物15立体选择性地转化为高度取代的呋喃糖31或取代的吡喃衍生物33,展示了芳基取代的8-杂双环[3.2.1]辛烯衍生物(如15)的巨大合成潜力,这些产物是通过简短而有效的反应序列得到的。