基于ortho-Quinone Methides类型的钯催化[4+3]不对称环加成反应研究

During the development of methods to organic synthesis, the emergence of the enantioselective cycloaddition reactions by palladium catalysts provides an atom-economic strategy, which dramatically shorten the pathway to the construction of carbon-carbon or carbon-heteroatom bonds and has achieved great progress in the synthesis of many useful polyfunctional chiral compounds. o-Quinone methides (o-QMs) are important intermediates in organic synthesis and materials chemistry as well as biological processes. However, although significant progress in cycloaddition reactions has been achieved with the assistance of organocatalysis, there are no studies on the palladium catalyzed enantioselective [4+3] annulation of o-QMs, which is very necessary to develop knowledge and associated strategies for overcoming these hurdles. In our project, we will develop some mild, highly efficient and enantioselective methods to realize the asymmetric cycloaddition of o-QMs with 1,3-dipole reagents with the assistance of chiral ligands and bifunctional organocatalyst through the procedure of oxidative addition, decarboxylation, desilication and tandem cyclization. The main contents including: 1) Palladium catalyzed enantioselective [4+3] annulation of o-QMs with vinylcyclopropanes. 2) Palladium catalyzed decarboxylative [4+3] asymmetric annulation of o-QMs with vinylethylene carbonates. 3) Palladium catalyzed enantioselective [4+3] cycloaddition of o-QMs with trimethylenemethane. The implementation of this project will make great contribution to the field of organic synthesis methodology with transition-metal catalysis.

钯催化的不对称环加成反应是近年来有机化学领域中十分活跃且极具挑战性和创新性的研究课题之一，备受有机化学工作者的关注。o-QMs作为杂原子共轭双烯参与的不对称环加成反应已经取得了一些重要进展，但是过渡金属催化特别是钯催化下的[4+3]不对称环加成反应仍然是一个全新的课题，非常值得深入研究。本项目利用金属钯催化，通过氧化加成、脱羧脱硅、串联环化等手段，结合手性配体及双功能有机催化剂的调控，探索钯催化下各类1,3-dipole合成子对o-QMs的不对称环加成反应，拟在以下三个方面开展研究工作：(1)钯催化下烯基三元环对o-QMs的不对称[4+3]环加成反应；(2)钯催化下五元内脂环对o-QMs的脱羧不对称[4+3]环加成反应；(3)钯催化下trimethylenemethanes对o-QMs的不对称[4+3]环加成反应。该项目的成功实施将会对过渡金属催化下有机合成方法学的发展和应用做出贡献。

环加成反应是近年来有机化学领域中十分活跃且极具挑战性和创新性的研究课题之一，备受有机化学工作者的关注。环丙烯酮做为一种特殊的Michael受体，其参与环加成反应的原理和途径与o-QMs有着相通之处。近年来，通过金属催化实现环丙烯酮的开环/环化反应研究非常有限。因此，深入开展环丙烯酮的环化反应，开发其作为C3合成子的研究仍然是一个全新的课题，非常值得研究。本项目通过调控金属催化剂来实现环丙烯酮的选择性开环方式(1,4加成开环)，采用β-C消除的策略原位形成C-M金属中间体，再对该中间体进行捕获从而实现环状化合物的高效构筑。通过本项目，1) 我们实现了环丙烯酮和N,N-二甲基甲酰胺的[3+2]环加成反应，高效制备了五元环γ-丁内酯骨架结构衍生物；2) 我们实现了硝酮对环丙烯酮的开环反应，为二酰胺类化合物的高效合成提供了全新的方法。此外，3)在肟醚为导向基团辅助的条件下，我们实现了芳环sp2 C-H键对马来酰亚胺的1,4-加成反应，高效制备了各种琥珀酰亚胺类衍生物；4) 实现了8-甲基喹啉类sp3 C-H键对马来酰亚胺的1,4-加成，为该类型化合物的合成提供了全新的途径。