Direct incorporation of two carbonyl groups into a double bond by diacylation is achieved for the first time via visible-light catalysis. Key to success is that N(n-Bu)4+ not only associates with the alkyl anion to avoid protonation, but also activates the α-keto acid to undergo electrophilic addition. The metal-free, redox-neutral and regioselective symmetric and unsymmetric 1,2-dicarbonylation of
通过可见光催化,首次实现了通过二酰化将两个羰基直接结合到双键中。成功的关键是 N( n -Bu) 4 +不仅与烷基阴离子缔合以避免质子化,而且还激活α-酮酸进行亲电加成。烯烃的无金属、氧化还原中性和区域选择性对称和不对称 1,2-二羰基化具有许多应用的潜力。
Cooperative NHC and Photoredox Catalysis for the Synthesis of 1,4-Dicarbonyl Compounds via Diacylation of Alkenes
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。
The diverse carbenic and cationic chemistry of 3-diazo-2,5-diphenylpyrrole
作者:M. Nagarajan、H. Shechter
DOI:10.1021/jo00175a012
日期:1984.1
A Novel One-Pot Pyrrole Synthesis via a Coupling−Isomerization−Stetter−Paal−Knorr Sequence
作者:Roland U. Braun、Kirsten Zeitler、Thomas J. J. Müller
DOI:10.1021/ol0165185
日期:2001.10.1
[GRAPHICS]1,2,3,5-Tetrasubstituted pyrroles can be synthesized in good yields in a one-pot, three-step, four-component process by a coupling-isomerization-Stetter reaction-Paal-Knorr sequence of an electron-poor (hetero)aryl halide, a terminal propargyl alcohol, an aldehyde, and a primary amine. The structures of the 1,4-diketone 4f and the pyrrole 6b were additionally supported by X-ray structure analyses.
NAGARAJAN, M.;SHECHTER, H., J. ORG. CHEM., 1984, 49, N 1, 62-74