硼自由基与不饱和体系的串联反应研究

有机硼化合物在合成化学领域发挥了至关重要的作用，迄今，多种硼化方法被开发。尽管如此，发展高选择性（包括区域选择性，化学选择性和立体选择性）、无过渡金属参与并且应用潜能广泛的新型硼化方法，仍然是一个极具挑战性的难题。在前期工作中，我们应用硼自由基与1,6-炔烯的高选择性自由基硼化/环化串联反应合成了一系列硼取代环状化合物。在此基础上，本项目将深入研究硼自由基与双烯、不饱和氰胺的反应，以及硼自由基引发的自由基加成移位环化反应。我们将精心设计底物结构，广泛筛选反应条件，为类型多样和结构复杂的硼取代环状化合物的制备提供高效温和、无过渡金属参与并且高选择性的新途径。通过对反应机理的研究，探明硼自由基的反应性能，并阐明影响反应选择性的因素。我们也试图将硼取代的环状化合物应用于药物分子和天然产物的合成，拓展这类串联反应在有机合成中的应用。

Organoboron compounds have played a significant role in modern synthetic chemistry. To date, a large number of borylation methods have been developed. Nevertheless, exploration of transition-metal-free approaches that allow for synthesis of complex organoboron compounds with high efficiency and selectivity (including regioselectivity, chemoselectivity and stereoselectivity) remains challenging. In our previous work, a highly selective method to construct boron-handled cyclic molecules was developed based on radical borylation/cyclization cascade of boryl radicals with 1,6-enynes. Encouraged by this result, in this project, we will investigate the radical cascade reactions of boryl radicals with dienes and unsaturated cyanoamines. Meanwhile, boryl radicals initiated radical addition-translocation-cyclization reactions will be studied as well. For these purposes, we will focus on: 1) designing substrates that can undergo varied radical cascade processes which are initiated by radical borylation reactions; 2) screening the reaction conditions, including boryl radical precursors, radical initiators, and reaction parameters; 3) studying the reaction mechanism to uncover the reactivity of boryl radicals and figure out the factors that influence the chemo-, regio-, and stereoselectivities. Eventually, the resulted boron-substituted cyclic products will be used for the synthesis of drug molecules and natural products. We expect that the implementation of this project will provide new approaches to construct boron-containing cyclic scaffolds, which may have versatile uses in synthetic and medicinal chemistry.