High Symmetry Catalysts in Organic Synthesis

在有机合成项目的支持下，Huw M. L.位于布法罗的纽约州立大学化学系的戴维斯正在研究高对称催化剂在有机合成中的应用。几个相同的低对称性配体围绕一个中心金属核的配位导致高对称性手性配合物。因此，具有两个C2-对称的磷酸联萘酯配体的二铑配合物是D2-对称的，而具有四个磷酸联萘酯配体的二铑配合物是D4-对称的。这类配合物催化的三种基本反应类型正在研究中。高度立体选择性的不对称C-H活化是通过分子间类卡宾诱导的C-H插入来实现的。组合的C-H插入/科普重排方案导致碳-碳键形成，在两个立体中心和两个双键处具有潜在的立体化学控制。最后，乙烯基类卡宾和乙烯基醚之间的[3+2]环加成反应生成高度官能化的环戊烯，其在三个立体中心处具有优异的立体控制。这些分子可能与不期望的化合物不同，因为它们之间的关系看起来像左手和右手之间的关系一样微妙（即，镜像），并且用于选择性合成这些分子的方法的开发仍然是一个重大的挑战。Huw M.教授L.位于布法罗的纽约州立大学化学系的戴维斯因其对选择性合成此类有机分子的新方法的研究而受到有机合成计划的支持。通过制备具有精心设计的对称性的催化剂，Davies教授影响了各种反应，特别是那些涉及将新的碳中心插入到碳-氢键中的反应，这使得可以构建具有高度立体化学控制的更复杂的产物。

With the support of the Organic Synthesis Program, Professor Huw M. L. Davies, of the Department of Chemistry, State University of New York at Buffalo, is studying the use of high symmetry catalysts in organic synthesis. Coordination of several identical low-symmetry ligands around a central metal core leads to high-symmetry chiral complexes. Thus, dirhodium complexes bearing two C2-symmetric binaphthylphosphate ligands are D2-symmetric, while those with four binaphthylphosphate ligands are D4-symmetric. Three basic reaction types catalyzed by such complexes are under investigation. Highly stereoselective asymmetric C-H activation is effected by means of intermolecular carbenoid-induced C-H insertion. Combined C-H insertion/Cope rearrangement protocols lead to carbon-carbon bond formation with potential control of stereochemistry at two stereogenic centers and two double bonds. Finally, [3+2] cycloaddition between vinylcarbenoids and vinyl ethers generates highly functionalized cyclopentenes with excellent stereocontrol at three stereogenic centers.Many of the complex organic molecules displaying desirable properties as pharmaceutical agents contain groupings of atoms with precisely defined geometric ("stereochemical") relationships. These molecules may differ from undesired compounds through as seemingly subtle a relationship as that between one's left and right hands (i.e., mirror images), and the development of methods for the selective synthesis of such molecules remains a significant challenge. Professor Huw M. L. Davies, of the Department of Chemistry, State University of New York at Buffalo, is supported by the Organic Synthesis Program for his studies of new methods for the selective synthesis of such organic molecules. By the preparation of catalysts with carefully designed symmetry, Professor Davies effects a variety of reactions, particularly those involving the insertion of new carbon centers into carbon-hydrogen bonds, which allow for the construction of more complex products with a high degree of stereochemical control.