SYNTHETIC UTILITY OF ELECTROPHILIC METAL PI-COMPLEXES

提出了一项研究计划，其主要目标是 开发综合有用的方法，主要来自 亲电金属Pi-配合物（炔丙基）Co-2（CO）6+（1）， （烯丙基）Fe（CO）4+（2）和（二烯）Co（CO）L 3+（3）。 先前的工作已经 建立了许多碳原子的容易的，区域选择性的偶联， 亲核试剂与配合物1和几种衍生物。 这项建议 试图检查立体化学，并利用这些新的变化， 在合成选定的、代表性的生物活性物质中的反应 化合物和关键中间体，包括海洋乙炔、大环 抗生素、圭亚那烷和假圭亚那烷倍半萜（细胞毒性， 抗肿瘤），和具有修饰侧链的类固醇（性激素， 抗肿瘤剂、维生素代谢物）。 在初步研究了2与选定的 亲核试剂通常指向高的区域选择性和立体选择性 偶联，最近发现了铁催化的烯丙基烷基化。 今后的工作重点将是：1）界定这些铁的范围 关于亲核试剂、底物及其催化反应， 对区域和立体选择性的影响; 2）比较这些反应 2和（n-2-allylX）Fe（CO）4的化学计量对应物; 和3）检查与烯丙基亲核试剂作为区域-和立体- 选择性异戊二烯基化方法。 最后，对准备和 亲电n-4-二烯配合物的反应性，3将进行。 感兴趣的主要问题包括区域和立体选择性的 亲核试剂攻击3。 开发综合有用的 这些研究的方法可能在未来适用于 构建复杂的天然产物。

A research program is proposed which has as its primary objective the development of synthetically useful methodologies derived primarily from the electrophilic metal Pi- complexes (propargyl)Co-2(CO)6+ (1), (allyl)Fe(CO)-4+ (2), and (diene)Co(CO)L-3+ (3). Previous work has established the facile, regioselective coupling of numerous carbon nucleophiles with the complexes 1 and several derivatives. This proposal seeks to examine the stereochemistry and to utilize new variations of these reactions in the synthesis of selected, representative biologically active compounds and key intermediates including marine acetylenes, macrocyclic antibiotics, guiane and pseudoguiane sesquiterpenes (cytotoxic, anti-tumor), and steroids with modified side chains (sex hormones, anti-tumor agents, vitamin metabolites). Following preliminary studies of the reactions of 2 with selected nucleophiles which point towards generally high regio- and stereoselective couplings, iron-catalyzed allylic alkylation has recently been discovered. Future efforts will focus on: 1) defining the scope of these iron catalyzed reactions with respect to nucleophiles, substrates, and their influence on regio- and stereoselectivity; 2) comparing these reactions with their stoichiometric counterparts, those of 2 and (n-2-allylX)Fe(CO)4; and 3) examining reactions with allyl nuleophiles as a regio- and stereo- selective isoprenylogation methodology. Finally, fundamental "ground-breaking" studies of the preparation and reactivity of electrophilic n-4-diene complexes, 3 will be conducted. Chief questions of interest include the regio- and stereoselectivity of attack on 3 by nucleophiles. Development of synthetically useful methodologies from these studies may have future applicability in the construction of complex natural products.