Flexible Strategy for the Synthesis of Pyrrolizidine Alkaloids
作者:Timothy J. Donohoe、Rhian E. Thomas、Matthew D. Cheeseman、Caroline L. Rigby、Gurdip Bhalay、Ian D. Linney
DOI:10.1021/ol801415d
日期:2008.8.21
A general strategy for the production of pyrrolizidinealkaloids is described, starting from intermediate (+)-9. The key features are diastereoselective dihydroxylation, inversion at the ring junction by hydroboration of an enamine, and ring closure to form the bicyclo ring system. This route is attractive because of its brevity and versatility; four natural products were prepared with differing stereochemistry
从中间体(+)-9开始,描述了制备吡咯烷核生物碱的一般策略。主要特征是非对映选择性二羟基化,烯胺的氢硼化在环结处发生转化以及闭环形成双环系统。该路线之所以具有吸引力,是因为它的简洁性和多功能性。制备了四种具有不同立体化学和取代模式的天然产物。最后,这项工作允许分配2,3,7-triepiaustraline和hyacinthacine A 7的绝对立体化学。
First total synthesis and absolute configuration of naturally occurring (−)-hyacinthacine A7 and its (−)-1-epi-isomer
作者:Isidoro Izquierdo、María T. Plaza、Juan A. Tamayo、Víctor Yáñez、Daniele Lo Re、Fernando Sánchez-Cantalejo
DOI:10.1016/j.tet.2008.03.009
日期:2008.5
A convergent synthesis of the naturallyoccurring alkaloid (−)-hyacinthacine A7, a glycosidase inhibitor of the pyrrolizidine class, is described. The homochiral starting material was tri-orthogonally protected DMDP 10, derived from d-fructose. Key steps of the synthesis were the carbon-chain lengthening at C(5′) in 10 to the α,β-unsaturated pyrrolidine ketone 12 and the one-pot construction of the
(+)-Hyacinthacines A 6 and A 7 have been synthesized from a common, late-stage intermediate, prepared in high yield through stereoselective [2+2] cycloaddition of dichloroketene to a chiral enol ether. The flexibility of aminonitrile chemistry is central to the approach.
(+)-Hyacinthacines A 6 和 A 7 是由常见的后期中间体合成的,通过二氯乙烯酮与手性烯醇醚的立体选择性 [2+2] 环加成反应以高收率制备。氨基腈化学的灵活性是该方法的核心。