Department of Pharmaceutical Analysis, School of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China.
Org Biomol Chem. 2020 May 13;18(18):3522-3526. doi: 10.1039/d0ob00551g.
para-Quinone methides bearing an electron-withdrawing cyano group at the exocyclic methylene δ-position were identified as valuable 1,6-conjugate addition building blocks for acyclic all-carbon quaternary stereocenter construction. A wide variety of electron-rich arenes as nucleophiles were tolerated, effectively furnishing diverse unsymmetrical triarylmethanes bearing all-carbon quaternary stereocenters. The robust transformable abilities of the cyano group provide a platform to access other valuable functional group-containing unsymmetrical tri- and tetraarylmethanes that are otherwise difficult to be prepared. Computational studies supported the hypothesis that the cyano group at the δ-position tunes the molecular electron-density distribution, and the stability of para-quinone methides is enhanced by lowering their polymerizability.
具有吸电子氰基的对位醌甲川化合物被确定为有价值的 1,6-共轭加成构建块，可用于构建非环全碳季碳立体中心。各种富电子芳环作为亲核试剂都能被容忍，有效地提供了各种带有全碳季碳立体中心的不对称三芳基甲烷。氰基的强大转化能力为获得其他有价值的含官能团的不对称三芳基和四芳基甲烷提供了平台，否则这些化合物很难制备。计算研究支持了这样的假设，即 δ-位的氰基基团调节分子的电子密度分布，并且通过降低其聚合度来增强对位醌甲川化合物的稳定性。
