Exploiting the Pd- and Ru-catalyzed cycloisomerizations: enantioselective total synthesis of (+)-allocyathin B2.
Exploiting the Pd- and Ru-catalyzed cycloisomerizations: enantioselective total synthesis of (+)-allocyathin B2.
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DOI：
10.1021/ja051547m
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发表时间：
2005-07
影响因子：
15
通讯作者：
B. Trost;Li Dong;Gretchen M. Schroeder
中科院分区：
文献类型：
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作者：
B. Trost;Li Dong;Gretchen M. Schroeder
比较了钯和钌催化的1，6-烯炔环异构化反应。这些考虑导致了对映选择性合成一种花青苷萜类化合物，（+）-别花青苷B（2）（1）。该合成的特点是Pd催化的不对称烯丙基烷基化（AAA）安装初始的季中心，Ru催化的非对映选择性环异构化，以构建六元环，和非对映选择性羟基化Knoevenagel反应，以引入最终的羟基。我们证明了第一次在Pd和Ru催化的环异构化反应，以及在创建烯烃的几何形状与炔带有烷氧羰基的立体化学分歧的机制。提出了这些意见的机制合理化。
Pd- and Ru-catalyzed cycloisomerizations of 1,6-enynes are compared and contrasted. Such considerations led to the enantioselective synthesis of a cyathin terpenoid, (+)-allocyathin B(2) (1). The synthesis features a Pd-catalyzed asymmetric allylic alkylation (AAA) to install the initial quaternary center, a Ru-catalyzed diastereoselective cycloisomerization to construct the six-membered ring, and a diastereoselective hydroxylative Knoevenagel reaction to introduce the final hydroxyl group. We demonstrate for the first time a mechanism-based stereochemical divergence in Pd- and Ru-catalyzed cycloisomerization reactions as well as in creation of alkene geometry with alkynes bearing a carboalkoxy group. Mechanistic rationalization is proposed for these observations.