[3,3]-sigma重排反应是一种高效的C-C键构建策略。在最近的研究中，我们发现beta,gamma-不饱和醛、酮等的羰基在Lewis酸作用下，可以被另一分子羰基氧或者亚胺氮亲核进攻，构成一个新颖的两性离子[3,3]-sigma重排体系，即oxy-2-oxonia-Cope以及oxy-2-azonia-Cope重排。重排后形成高烯丙酯以及高烯丙基酰胺类化合物。本课题中我们将系统地考察底物结构对此重排的影响，探讨[5,5]-sigma重排反应的可行性，研究在手性Lewis酸催化下的不对称重排，并建立基于这种重排合成氨基酸的新方法，完成若干Motuporamines生物碱等具有重要生理活性的海洋天然产物的合成，发展新的扩环反应策略。我们还将结合实验，采用理论计算方法，揭示重排底物中取代基种类、取代位置对反应的影响规律。该项研究工作是一项具有重要的学术意义和突出的应用价值的课题。

Various [3,3]-sigma rearrangement reactions constitute an invaluable class of methodologies for the atom-economical formation of carbon-carbon bond, and have found many applications as the key step in the total synthesis of natural products. Quite recently, in an attempt to synthesize a potential oxaspiro odorant by Prins reaction, we disclosed that beta,gamma-unsaturated ketones and alkoxy oximes or imines undergo nucleophilic addition to produce zwitterion intermediates, which subsequently afford homoallylic esters or amides by oxy-azonia and oxy-oxonia-Cope [3,3]-sigma rearrangement. Further, the concept was evolved to intramolecular version, leading to homoallylic macrolide or microlactams. Using this convergent and atom-economical [n+4] ring enlargement strategy, the total synthesis of alkaloid motuporamine G was completed and the structure was verified. In the present study, novel substrates including 4-oxo-alkynes, imines derived from aldehyde/keto carboxylic acids or esters, and beta,gmma,delta,epslong-unsaturated carbonyl compounds will be investigated. The substituent effects are to be analyzed by considering the effect on reactants, products, and the TS. The alkaloids motuporamines A, B, and C, which were isolated as an inseparable mixture from Xestospongia exigua collected in Papua New Guinea, represent a new family of cytotoxic sponge alkaloids containing a spermidine-like substructure. On the basis of the reaction scope study, the chemical synthesis will be explored. Meanwhile, chiral version of these valuable transformations by using chiral Lewis acids will be approached. Representative reactions will also be investigated computationally using density functional theory. This work is of primary importance to broaden the synthetic application of these novel oxy-oxonia-Cope and oxy-azonia-Cope rearrangements, and to obtain deeper insight in the nature of these reactions.