CATALYTIC REDUCTIVE CYCLIZATION

这项建议的目标是发展过渡金属-- 中介的两个不饱和中心的还原耦合成一个一般的， 碳-碳键形成的催化、立体选择性方法 碳环和杂环有机靶分子中。一个值得注意的问题 过渡金属催化还原偶联反应的优势 是对映选择性转换可以通过 一种廉价的无手性化学计量比还原剂 手性过渡金属络合物的亚化学计量比 (不对称催化)。这样的过程将是一个有价值的替代方案 使用昂贵的还原剂的还原偶联协议 化学计量的量。 我们建议研究钛氧金属环的化学和 通过还原环化形成的相关物种(例如，氮杂环， 锆金属循环)，目标是开发有用的合成 高度官能化的立体控制合成方案 碳环和杂环化合物。特别是，我们将发展 还原环化反应的新催化方法。

The objective of this proposal is to develop the transition metal- mediated reductive coupling of two unsaturated centers into a general, catalytic, stereoselective method for formation of carbon-carbon bonds within carbocyclic and heterocyclic organic target molecules. A notable advantage of the transition metal-catalyzed reductive coupling reaction is that enantioselective transformations can be effected with an inexpensive, achiral stoichiometric reductant in the presence of a substoichiometric quantity of a chiral transition metal complex (asymmetric catalysis). Such a process will be a valuable alternative to reductive coupling protocols which employ an expensive reducing agent in stoichiometric quantities. We propose to study the chemistry of the titanium oxometallacycles and related species formed by reductive cyclization (e.g., azametallacycles, zirconium metallacycles) with the goal of developing useful synthetic protocols for the stereocontrolled synthesis of highly functionalized carbocyclic and heterocyclic compounds. In particular, we will develop new catalytic methods for reductive cyclization.