intermolecular 1,2-diacylation of alkenes is disclosed via cooperative N-heterocyclic carbene and photoredox catalysis under the mediation of PPh3 and Cs2CO3. This protocol provides a practical approach for construction of 1,4-dicarbonyl compounds toward novel diketone and pharmaceutical derivatives. Furthermore, the regioselective dicarbonyl compounds can be synthesized by adding acyl azolium salt. Mechanistic
在PPh 3和Cs 2 CO 3的介导下,通过协同的N-杂环卡宾和光氧化还原催化烯烃的分子间1,2-二酰化被公开。该协议为向新型二酮和药物衍生物构建 1,4-二羰基化合物提供了一种实用的方法。此外,区域选择性二羰基化合物可以通过添加酰基唑鎓盐来合成。机理研究表明,该过程是酮基自由基与苄基 C-自由基的关键自由基/自由基交叉偶联。
Photoinduced Acylations Via Azolium-Promoted Intermolecular Hydrogen Atom Transfer
作者:Joshua L. Zhu、Cullen R. Schull、Anthony T. Tam、Ángel Rentería-Gómez、Achyut Ranjan Gogoi、Osvaldo Gutierrez、Karl A. Scheidt
DOI:10.1021/jacs.2c12845
日期:2023.1.25
Photoinduced hydrogenatomtransfer (HAT) has been developed as a powerful tool to generate synthetically valuable radical species. The direct photoexcitation of ketones has been known to promote HAT or to generate acyl radicals through Norrish-type pathways, but these modalities remain severely limited by radical side reactions. We report herein a catalyst- and transition metal-free method for the
光致氢原子转移 (HAT) 已被开发为生成具有合成价值的自由基物种的强大工具。已知酮的直接光激发可促进 HAT 或通过 Norrish 型途径产生酰基自由基,但这些方式仍然受到自由基副反应的严重限制。我们在此报告了一种无催化剂和过渡金属的 C-H 键酰化方法,该方法利用了稳定、可分离的酰基唑鎓物种的独特性质。具体而言,酰基唑盐显示在 LED 照射下会发生分子间和区域选择性 HAT,一系列底物带有活性 C-H 键,随后形成 C-C 键以提供酮。
Ketone Synthesis via Irradiation-Induced Generation of a Persistent Ketyl Radical from Acyl Azolium Salts
A novel three-component α-acylated difunctionalization of alkenes strategy has been developed on the basis of a direct hydrogen atom transfer (HAT) process of photoinduced acyl azolium salts. With simple irradiation without the catalyst, a variety of olefins can be directly converted into ketone derivatives, including 1,4-dione, β-silyl ketone, 1,5-dione, etc. Mechanistic investigations indicated that
Pd‐catalyzed oxidative coupling of 2‐aroylimidazoles with benzyl alcohols: Access to imidazole functionalized phthalazines and phthalazin‐1(2
<i>H</i>
)‐ones
作者:Ruike Zhang、Yuqiu Guan、Baodong Tian、Yong Liu、Zhangpei Chen、Jianshe Hu
DOI:10.1002/aoc.7060
日期:2023.4
conditions has been achieved to furnish a variety of carbonyl functionalized 2-aroylimidazoles in moderate to good yields. The obtained products could be selectively transformed to the corresponding phthalazines and phthalazin-1(2H)-ones with hydrazine hydrate as the cyclization partner under different reaction temperature and construct an array of structurally diverse nitrogen-containing heterocycles.
钯催化的 2-芳酰咪唑与芳香醛或苯甲醇在氧化条件下的直接氧化偶联反应已经实现,以提供各种羰基官能化的 2-芳酰咪唑,收率中等至良好。所获得的产物可以在不同反应温度下以水合肼为环化配偶体选择性地转化为相应的酞嗪和酞嗪-1(2 H )-化合物,构建一系列结构多样的含氮杂环化合物。