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Huw M. L. Davies教授正在研究高对称性催化剂在有机合成中的应用。几个相同的低对称配体围绕中心金属核的配位导致高对称手性配合物。因此，含有两个c2对称的二磷酸二萘基配体的钯配合物是d2对称的，而含有四个二磷酸二萘基配体的钯配合物是d4对称的。目前正在研究由这类配合物催化的三种基本反应类型。高立体选择性的不对称碳氢活化是通过类碳水化合物分子间诱导的碳氢插入来实现的。C-H插入/Cope重排组合方案导致碳-碳键的形成，并在两个立体中心和两个双键上具有立体化学的潜在控制。最后，在乙烯基类羰基和乙烯基醚之间进行[3+2]环加成反应，生成高度官能化的环戊烯，在三个立体中心具有良好的立体控制能力。许多复杂的有机分子都含有具有精确定义的几何（“立体化学”）关系的原子群。这些分子可能与不想要的化合物不同，因为它们之间的关系似乎很微妙，就像人的左手和右手之间的关系（即镜像）一样，而选择性合成这些分子的方法的发展仍然是一个重大的挑战。纽约州立大学布法罗分校化学系的Huw M. L. Davies教授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。通过精心设计对称的催化剂制备，Davies教授影响了各种反应，特别是那些涉及将新碳中心插入碳氢键的反应，这使得构建具有高度立体化学控制的更复杂的产物成为可能。

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.