Radical Dehydroxylative Alkylation of Tertiary Alcohols by Ti Catalysis,Journal of the American Chemical Society

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Radical Dehydroxylative Alkylation of Tertiary Alcohols by Ti Catalysis
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-09-04 , DOI: 10.1021/jacs.0c07492
Hao Xie ₁ , Jiandong Guo ₂ , Yu-Quan Wang ₁ , Ke Wang ₁ , Peng Guo ₁ , Pei-Feng Su ₁ , Xiaotai Wang _{2,

3} , Xing-Zhong Shu ₁

Affiliation

Deoxygenative radical C-C bond-forming reactions of alcohols are a long-standing challenge in synthetic chemistry, and the current methods rely on multistep procedures. Herein, we report a direct dehydroxylative radical alkylation reaction of tertiary alcohols. This new protocol shows the feasibility of generating tertiary carbon radicals from alcohols and offers an approach for the facile and precise construction of all-carbon quaternary centers. The reaction proceeds with a broad substrate scope of alcohols and activated alkenes. It can tolerate a wide range of electrophilic coupling partners, including allylic carboxylates, aryl and vinyl electrophiles, and primary alkyl chlorides/bromides, making the method complementary to the cross-coupling procedures. The method is highly selective for the alkylation of tertiary alcohols, leaving secondary/primary alcohols (benzyl alcohols included) and phenols intact. The synthetic utility of the method is highlighted by its 10-gram-scale reaction and the late-stage modification of complex molecules. A combination of experiments and DFT calculations establishes a plausible mechanism implicating a tertiary carbon radical generated via Ti-catalyzed homolysis of the C-OH bond.

中文翻译：

钛催化叔醇自由基脱羟基烷基化

醇的脱氧自由基 CC 键形成反应是合成化学中长期存在的挑战，目前的方法依赖于多步骤程序。在此，我们报告了叔醇的直接脱羟基自由基烷基化反应。这一新协议显示了从醇类中生成叔碳自由基的可行性，并为轻松精确地构建全碳四元中心提供了一种方法。该反应在醇和活化烯烃的广泛底物范围内进行。它可以耐受各种亲电偶联伙伴，包括烯丙基羧酸盐、芳基和乙烯基亲电试剂以及伯烷基氯/溴化物，使该方法与交叉偶联程序形成互补。该方法对叔醇的烷基化具有高度选择性，保持仲醇/伯醇（包括苯甲醇）和酚类完好无损。该方法的合成效用因其 10 克规模的反应和复杂分子的后期修饰而突出。实验和 DFT 计算的组合建立了一个合理的机制，暗示通过 Ti 催化的 C-OH 键均裂产生叔碳自由基。

更新日期：2020-09-04

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