Leger Paul R, Murphy Rebecca A, Pushkarskaya Eugenia, Sarpong Richmond
Department of Chemistry, University of California, Berkeley, Latimer Hall, Berkeley, CA 94720 (USA), Fax: (+1) 510-642-9675.
Chemistry. 2015 Mar 9;21(11):4377-83. doi: 10.1002/chem.201406242. Epub 2015 Jan 30.
Progress toward the total syntheses of a diverse set of fawcettimine-type Lycopodium alkaloids via a "Heathcock-type" 6-5-9 tricycle is disclosed. This route features an intermolecular Diels-Alder cycloaddition to rapidly furnish the 6-5-fused bicycle and a highly chemoselective directed hydrogenation to build the azonane fragment. While conducting these synthetic studies, trimethylsilyl iodide was found to effect a hydroamination reaction to furnish the tetracyclic core of serratine and related natural products. This observation has been expanded into a general method for the room temperature hydroamination of unactivated olefins with tosylamides utilizing catalytic "anhydrous" HI (generated in situ from trimethylsilyl iodide and water). The presence of the iodide anion is critical to the success of this Brønsted acid catalyzed protocol, possibly due to its function as a weakly coordinating anion. These conditions also effect the analogous hydroetherification reaction of alcohols with unactivated olefins.
本文披露了通过“希思科克型”6-5-9三环实现多种石松胺型石松生物碱全合成的进展。该路线的特点是分子间狄尔斯-阿尔德环加成反应能快速构建6-5稠合双环,以及高度化学选择性的导向氢化反应来构建氮杂环壬烷片段。在进行这些合成研究时,发现碘化三甲基硅烷能引发氢胺化反应,从而得到锯齿石松碱及相关天然产物的四环核心。这一发现已扩展为一种通用方法,可利用催化量的“无水”HI(由碘化三甲基硅烷和水原位生成),在室温下实现未活化烯烃与对甲苯磺酰胺的氢胺化反应。碘离子的存在对这种布朗斯特酸催化反应的成功至关重要,这可能是由于其作为弱配位阴离子的作用。这些条件还能实现醇与未活化烯烃的类似氢醚化反应。