Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States.
Research Computing Center , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3420 , United States.
J Am Chem Soc. 2019 Feb 13;141(6):2645-2651. doi: 10.1021/jacs.8b13006. Epub 2019 Jan 30.
Feedstock aromatic compounds are compelling low-cost starting points from which molecular complexity can be generated rapidly via oxidative dearomatization. Oxidative dearomatizations commonly rely heavily on hypervalent iodine or heavy metals to provide the requisite thermodynamic driving force for overcoming aromatic stabilization energy. This article describes oxidative dearomatizations of 2-(hydroxymethyl)phenols via their derived bis(dichloroacetates) using hydrogen peroxide as a mild oxidant that intercepts a transient quinone methide. A stereochemical study revealed that the reaction proceeds by a new mechanism relative to other phenol dearomatizations and is complementary to extant methods that rely on hypervalent iodine. Using a new chiral phase-transfer catalyst, the first asymmetric syntheses of 1-oxaspiro[2.5]octa-5,7-dien-4-ones were reported. The synthetic utility of the derived 1-oxaspiro[2.5]octadienones products is demonstrated in a downstream complexity-generating transformation.
原料芳烃化合物是极具吸引力的低成本起点，通过氧化脱芳烃可以快速生成分子复杂性。氧化脱芳烃通常严重依赖高价碘或重金属来提供克服芳烃稳定能所需的热力学驱动力。本文描述了通过 2-(羟甲基)苯酚的衍生双(二氯乙酸酯)进行氧化脱芳烃，使用过氧化氢作为温和氧化剂，拦截瞬态醌甲基化物。一项立体化学研究表明，该反应相对于其他苯酚脱芳烃具有新的机制，与依赖高价碘的现有方法互补。使用新型手性相转移催化剂，首次报道了 1-氧杂螺[2.5]辛-5,7-二烯-4-酮的不对称合成。衍生的 1-氧杂螺[2.5]辛二烯酮产物的合成实用性在后续的复杂性生成转化中得到了证明。
