Graduate School of Engineering, Nagoya University, Nagoya, Japan.
Nat Chem. 2020 Apr;12(4):353-362. doi: 10.1038/s41557-020-0433-4. Epub 2020 Mar 23.
ortho-Quinone methides are useful transient synthetic intermediates in organic synthesis. These species are most often generated in situ by the acid- or base-mediated transformation of phenols that have been pre-functionalized at a benzylic position, or by biomimetic oxidation of the corresponding ortho-alkylphenols with metal oxidants or transition-metal complexes. Here we describe a method for the transition-metal-free oxidative generation of o-QMs from ortho-alkylarenols, using hypoiodite catalysis under nearly neutral conditions, which can then be applied in one-pot tandem reactions. This method for the chemoselective oxidative generation of ortho-quinone methides may prove superior to previous methods with respect to environmental issues and scope, and can be applied to various tandem reactions such as inter- or intramolecular [4 + 2] cycloaddition, oxa-6π-electrocyclization, conjugate addition and spiroepoxidation.
邻醌甲叉化物是有机合成中有用的瞬态合成中间体。这些物质通常通过在苄位预官能化的酚的酸或碱介导的转化原位生成，或者通过用金属氧化剂或过渡金属配合物对相应的邻位烷基苯酚进行仿生氧化来生成。在这里，我们描述了一种在近中性条件下使用次碘酸盐催化从邻位烷芳醇中无过渡金属生成邻-QM 的方法，然后可以在一锅串联反应中应用。与以前的方法相比，这种邻醌甲叉化物的化学选择性氧化生成方法在环境问题和范围方面可能具有优势，并且可以应用于各种串联反应，如分子间或分子内[4 + 2]环加成、氧杂-6π-电环化、共轭加成和螺环氧化。
