NEW LIGANDS FOR ASYMMETRIC SYNTHESIS AND CATALYSIS

提出了开发一类手性配体用于 过渡金属和刘易斯酸介导的不对称反应， 有机合成具体地，这些是配体13、14、86、87、101 - 106、111和116。 所有这些配体都是2，2 '-联萘基或 3，3 '-联菲基衍生物。 这些配体都还没有被制造出来 在前面和初步结果部分中描述了 已开发用于合成13和14。拟议的合成 给出了其它配体。 提出了两种通用方法， 这些配体的制备。 氧化偶联方法已经被 证明对13和14是可行的，一些初步证据表明， 提出的建议，涉及苯并环化反应的方法， 铬碳烯络合物可能具有潜力。 最伟大的方面 这种可能性在于，碳烯络合物可以提供一种途径， 这些配体的不对称合成， 需要繁琐的解决程序。 在这些配体作为手性控制剂的初步评价中， 发现配体14的氯铝络合物给出高不对称性， 甲基丙烯醛与环戊二烯Diels-Alder反应的诱导 (98% ee），并且另外将产生200次周转（0.5摩尔%催化剂） 在-78 ℃下4小时。 可能的面部特征来源 对衍生自这些配体的催化剂观察到的选择性是 讨论 涉及新配体构建的几个实验 描述了旨在探索不对称性来源的方法 诱导 除了Diels-Aider反应之外，还提出 这些配体可以根据它们在不对称 杂原子Diels-Alder反应，羟醛反应，Claisen重排， 羰基加成、还原环化和碳代甲烷 反应.此外，应注意，这些配体具有一些结构上的特征。 与棉酚的关系，棉酚是一种天然存在的2，2 '-联萘， 存在于棉花种子和其他天然来源中。 鉴于已知 棉酚的生物学特性，建议其中一些 配体及其合成中的中间体可进行抗病毒试验 和抗癌活性。

A plan is presented to develop a class of chiral Iigands for use in transition metal and Lewis acid mediated asymmetric reactions of value in organic synthesis. Specifically, these are the ligands 13, 14, 86, 87,101 - 106, 111 and 116. All of these ligands are either 2,2'-binaphthyls or 3,3'-biphenanthryl derivatives. None of these ligands have been made before, and in the preliminary results section methods are described which have been developed for the synthesis of 13 and 14. Proposed syntheses of the other ligands are presented. Two general methods are presented for the preparation of these ligands. The oxidative coupling method has been shown to be viable for 13 and 14 and some preliminary evidence is presented to suggest that approaches involving the benzannulation reaction of chromium carbene complexes may have potential. The greatest aspect of this potential is that carbene complexes may provide a route for the asymmetric synthesis of these ligands which would obviate the normally tedious resolution procedures that are required. In a preliminary evaluation of these ligands as chiral controllers it was found that a chloroaluminum complex of ligand 14 gives high asymmetric induction in the Diels-Alder reaction of methacrolein and cyclopentadiene (98 % ee) and in addition will produce 200 turnovers (0.5 mole % catalyst) in 4 h at -78 degrees C. Possible sources of the particular facial selectivity observed for the catalysts derived from these ligands are discussed. Several experiments involving the construction of new ligands are described which are designed to probe the source of the asymmetric induction. In addition to the Diels-AIder reaction, it is proposed that these ligands be evaluated with regard to their utility in asymmetric heteroatom Diels-Alder reactions, aldol reactions, Claisen rearrangements, carbonyl additions, reductive cyclizations, and carbometallation reactions. In addition it is noted that these ligands bear some structural relationship to gossypol, a naturally occurring 2,2'-binaphthol which occurs in cotton seeds and other natural sources. Given the known biological properties of gossypol, it is suggested that some of these ligands and the intermediates in their syntheses be tested for antiviral and anticancer activity.