High Symmetry Catalysts in Organic Synthesis

在有机合成项目的支持下，纽约州立大学布法罗分校化学系的休·M·L·戴维斯教授正在研究高对称性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心配位，得到高对称性的手性配合物。因此，含有两个C2对称的双萘磷酸酯配体的镝配合物是D2对称的，而含有四个双萘磷酸酯配体的镝配合物是D4对称的。这类络合物催化的三种基本反应类型正在研究中。高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插入实现的。C-H插入/COPE重排的组合方案导致了碳-碳键的形成，潜在地控制了两个立体中心和两个双键的立体化学。最后，乙烯基卡宾和乙烯基醚之间的[3，2]环加成反应生成了高度官能化的环戊烯，在三个立体生成中心具有良好的立体控制。许多显示出理想的药物性质的复杂有机分子包含具有精确定义的几何(立体化学)关系的原子基团。这些分子可能与不受欢迎的化合物不同，因为它们之间的关系看起来很微妙，就像一个人的左手和右手之间的关系(即镜像)，而开发选择性合成此类分子的方法仍然是一个重大挑战。纽约州立大学布法罗分校化学系的休·M·L·戴维斯教授因研究选择性合成此类有机分子的新方法而得到有机合成计划的支持。通过精心设计的对称性催化剂的制备，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，这使得能够构建更复杂的产品，并具有高度的立体化学控制。

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.