GROUP VIA METAL COMPLEXES IN SYNTHESIS

描述：本提案的主要目标是开发 烯烃和二烯烃可控官能化的新方法 涉及VIA族过渡金属的有机金属化学。的 01年至04年的具体重点将是操纵 对烯丙基和二烯钼络合物;其他VIA族金属是 目前尚未考虑，但预计初步 在资助期内，可就其化学性质得出结果。 研究了无环π-烯丙基-Mo（CO）_2Cp体系在稳定 将研究邻近的碳负离子。先前观察到的不可逆性 这些碳负离子的重排将允许构建 立体化学定义的烯烃亚基是重要的结构 许多生物学上重要的分子的特征。的化学性质 由环状π-烯丙基-钼络合物产生的碳负离子，以及 作为环己二烯-钼的外部亲核试剂加成 复杂的，将被评估为方法的建设， 季碳中心将检查区域控制方法， 导致新的方法来合成重要的亚基， 石蒜科生物碱。内碳亲核试剂加成 二烯钼配合物将进行研究，导致方法， 螺环和其他复杂环系的构建。这 这将是亲电化合物的成环反应的第一个一般性研究。 二烯配合物，并将在快速发展的领域开辟新天地 使用有机金属配合物的有机合成。使用手性 连接到二烯和烯丙基溴的助剂，以实现 光学纯的π-烯丙基-和二烯-钼络合物的合成， 将进行研究，以预期允许所有上述 方法学应用于不对称有机合成。

DESCRIPTION: The principal goal of this proposal is the development of new methods for controlled functionalization of alkenes and dienes based on organometallic chemistry involving Group VIA transition metals. The specific focus in the 01 through 04 years will be on the manipulation of p-allyl- and diene-molybdenum complexes; other Group VIA metals are not considered at this time, but it is anticipated that preliminary results on their chemistry can be generated during the grant period. The role of an acyclic pi-allyl-Mo(CO)2Cp system in stabilizing a neighboring carbanion will be studied. Previously observed irreversible rearrangements of these carbanions will allow the construction of stereochemically defined olefinic subunits that are important structural features of many biologically important molecules. The chemistry of carbanions generated from cyclic pi-allyl-molybdenum complexes, as well as external nucleophile additions to cyclohexadiene-molybdenum complexes, will be evaluated as methodology for the construction of quaternary carbon centers. Methods for regiocontrol will be examined, leading to new approaches for the synthesis of important subunits of Amaryllidaceae alkaloids. Internal carbon nucleophile additions to diene-molybdenum complexes will be studied, leading to methodology for the construction of spirocyclic and other complex ring systems. This will be the first general study of annulation reactions of electrophilic diene complexes and will break new ground in the rapidly developing area of organic synthesis using organometallic complexes. The use of chiral auxiliaries attached to dienes and allylic bromides, to effect the synthesis of optically pure pi-allyl- and diene-molybdenum complexes, will be studied in anticipation of allowing all of the aforementioned methodology to be applied in asymmetric organic synthesis.