Selective Deprotonation in Acyclic Systems (Chemistry)

碳-碳键的构建仍然是构建新的有机分子的一个关键挑战。这一挑战隐含着在形成新键时实现选择性。本研究将探索碳-碳键选择性引入非环体系的新反应途径。期望的选择性将在通过杂原子辅助去质子化的碳离子的选择性形成中寻求。将研究的新反应类型包括：(1)乙烯基和二烯醚的直接锂化反应；(2)非亚砜体系中非环质子的非对映选择性去质子化；(3)分子内不稳定碳离子对酮和醛的加成作用。由这些反应产生的产物通常具有独特的结构，可以进行许多立体选择转化。例如，第一类在Diels-Alder反应中表现出完全pi面选择性的不对称二烯将通过二烯醚的定向去质子化而获得。只要有可能，就会提出和测试模型，以努力描绘附近杂原子对去质子化选择性的确切影响。基于这些知识，杂原子辅助去质子化可以合理地扩展到新的体系中，使其成为一种更强大的选择性键构建方法。

The construction of carbon-carbon bonds remains as a key challenge in the construction of new organic molecules. Implicit in this challenge is the achievement of selectivity in forming the new bond. This research will investigate new reaction pathways for the selective introduction of carbon-carbon bonds into acyclic systems. The desired selectivity will be sought in the selective formation of carbanions via a heteroatom-assisted deprotonation. New reaction types which will be studied include: (1) the direct beta-lithiation of vinyl and dienyl ethers; (2) the diastereoselective deprotonation of acyclic protons in systems other than sulfoxides; (3) the intramolecular addition of unstabilized carbanions to ketones and aldehydes. The products which result from these reactions are often unique structures which will lend themselves to numerous stereoselective transformations. For example, the first class of asymmetric dienes to exhibit complete pi-face selectivity in the Diels-Alder reaction will be available through the directed deprotonation of dienyl ethers. Whenever possible models will be proposed and tested in an effort to delineate the exact effect that nearby heteroatoms have on the selectivity of deprotonation. Based on this knowledge, heteroatom-assisted deprotonations can be rationally extended to new systems rendering it an even more powerful method for selective bond construction.