Neipp Christopher E, Martin Stephen F
Department of Chemistry and Biochemistry, The University of Texas, Austin, TX 78712, USA.
J Org Chem. 2003 Nov 14;68(23):8867-78. doi: 10.1021/jo0349936.
A new strategy for the facile synthesis of azabicyclo[m.n.1]alkenes (m = 3-5; n = 3, 2) has been developed that involves the ring-closing metathesis (RCM) reaction of cis-2,6-dialkenyl-N-acyl piperidine derivatives. The requisite 2,6-dialkenylpiperidines may be readily prepared in six steps starting from glutarimide (11) or three steps from 4-methoxypyridine (25). In one example that establishes the practical utility of the procedure, the functionalized 8-azabicyclo[3.2.1]octane 32, which is a potential intermediate for the syntheses of various tropane alkaloids, was prepared. Additionally, a new route for the construction of the bridged tetrahydro-beta-carboline ring system 5 has been developed that features the ring-closing metathesis of the enyne 45 to construct the bridging ring in 46. This concise route to 46 also features a potentially general and useful procedure for the one-step preparation of a terminal alkyne from an ester function. Selective oxidation of the vinyl group in 46 afforded the unsaturated aldehyde 47, which may serve as a useful intermediate in syntheses of several Sarpagine alkaloids.
已开发出一种简便合成氮杂双环[m.n.1]烯烃（m = 3 - 5；n = 3, 2）的新策略，该策略涉及顺式-2,6-二烯基-N-酰基哌啶衍生物的闭环复分解（RCM）反应。所需的2,6-二烯基哌啶可从戊二酰亚胺（11）开始经六步或从4-甲氧基吡啶（25）开始经三步轻松制备。在一个证明该方法实用性的实例中，制备了功能化的8-氮杂双环[3.2.1]辛烷32，它是合成各种托烷生物碱的潜在中间体。此外，已开发出一种构建桥连四氢-β-咔啉环系5的新路线，其特征在于烯炔45的闭环复分解以构建46中的桥环。这条通往46的简洁路线还具有一种潜在通用且有用的方法，可从酯官能团一步制备末端炔烃。46中乙烯基的选择性氧化得到不饱和醛47，它可作为几种蛇根碱生物碱合成中的有用中间体。
