713-36-0Relevant articles and documents
Development of highly efficient Friedel-Crafts alkylations with alcohols using heterogeneous catalysts under continuous-flow conditions
Kobayashi, Shū,Koumura, Nagatoshi,Masuda, Koichiro,Okamoto, Yukiko,Onozawa, Shun-Ya
, p. 24424 - 24428 (2021/07/29)
The development of Friedel-Crafts alkylations with alcohols under continuous-flow conditions using heterogeneous catalysts is reported. The reactivities and durabilities of the examined catalysts were systematically investigated, which showed that montmorillonite clay is the best catalyst for these reactions. A high turnover frequency of 9.0 × 102h?1was recorded under continuous-flow conditions, and the continuous operation was successfully maintained over one week.
Cascade Reductive Friedel-Crafts Alkylation Catalyzed by Robust Iridium(III) Hydride Complexes Containing a Protic Triazolylidene Ligand
Albrecht, Martin,Alshakova, Iryna D.
, p. 8999 - 9007 (2021/07/31)
The synthesis of complex molecules like active pharmaceutical ingredients typically requires multiple single-step reactions, in series or in a modular fashion, with laborious purification and potentially unstable intermediates. Cascade processes offer attractive synthetic remediation as they reduce time, energy, and waste associated with multistep syntheses. For example, triarylmethanes are traditionally prepared via several synthetic steps, and only a handful of cascade routes are known with limitations due to high catalyst loadings. Here, we present an expedient catalytic cascade process to produce triarylmethanes. For this purpose, we have developed a bifunctional iridium system as the efficient catalyst to build heterotriaryl synthons via reductive Friedel-Crafts alkylation from ketones, arenes, and hydrogen. The catalytically active species were generated in situ from a robust triazolyl iridium(III) hydride complex and acid and is composed of a metal-bound hydride and a proximal ligand-bound proton for reversible dihydrogen release. These complexes catalyze the direct hydrogenation of ketones at slow rates followed by dehydration. Appropriate adjustment of the conditions successfully intercepts this dehydration and leads instead to efficient C-C coupling and Friedel-Crafts alkylation. The scope of this cascade process includes a variety of carbonyl substrates such as aldehydes, (alkyl)(aryl)ketones, and diaryl ketones as precursor electrophiles with arenes and heteroarenes for Friedel-Crafts coupling. The reported method has been validated in a swift one-step synthesis of the core structure of a potent antibacterial agent. Excellent yields and exquisite selectivities were achieved for this cascade process with unprecedentedly low iridium loadings (0.02 mol %). Moreover, the catalytic activity of the protic system is significantly higher than that of an N-methylated analogue, confirming the benefit of the Ir-H/N-H hydride-proton system for high catalytic performance.
Method for reducing carbonyl reduction to methylene under illumination
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Paragraph 0033-0038; 0104-0108, (2021/09/29)
The invention belongs to the technical field of organic chemical synthesis. The method comprises the following steps: (1) mixing the carbonyl compound and the amine compound in a solvent, reacting 3 - 6 under the illumination of 380 - 456 nm, the reaction system is low in toxicity, high in atom utilization rate 12 - 24h. and production efficiency, safe and controllable in reaction process and capable of simplifying the operation in the preparation and production process. At the same time, the residue toxicity of the reaction is minimized, the pollution caused by the production process to the environment is reduced, and the steps and operations of removing residues after the reaction are simplified. In addition, the reactant feedstock is readily available. The reactant does not need additional modification before the reaction, can be directly used for preparing production, simplifies the operation steps, and shortens the reaction route. The production cost is obviously reduced.