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Версия для печати | Главная > Центр > Научные советы > Научный совет по катализу > ... > 2025 год > № 114

№ 114

 

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  • Всероссийская научная конференция «Пятый Байкальский материаловедческий форум» БМФ-2025
  • VII Всероссийская школа-конференция по катализу
    с международным участием «Каталитический дизайн:
    от исследований на молекулярном уровне к практической реализации
  • В.А. Лихолобов. Развитие концепции об «активных центрах в катализе»: Мишель Будар
  • Защита диссертаций в области катализа
  • За рубежом
  • Приглашения на конференции


Всероссийская научная конференция «Пятый Байкальский материаловедческий форум» БМФ-2025

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VII Всероссийская школа-конференция по катализу с международным участием «Каталитический дизайн: от исследований на молекулярном уровне к практической реализации»

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Развитие концепции об «активных центрах в катализе»: Мишель Будар

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Защита диссертаций в области катализа

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More cross-coupling with less metal

Low-cost sodium salt may enable chemists to assemble molecules more efficiently and safely


This new cross-coupling method is compatible with the precursors
to Suzuki-Miyaura coupling and other popular molecule-building methods.

Cross-coupling has been one of the most popular types of reactions in organic chemistry for decades. The pharma and agrochemical industries use these methods on a large scale to forge bonds between aromatic rings. One downside of these classic reactions is that they require one of the coupling partners to be fitted with an organometallic group before the coupling step.

Methods that let chemists bypass that premetalation step in favor of directly stitching together two aryl halides have been gaining momentum. Such methods could shorten syntheses and cut waste. But they often still require a reductant such as zinc or manganese for the catalytic cycle to work, which can pose safety problems on scale-up.

“These are useful reactions at the discovery level, but they're a little challenging to deploy on scale” because metal reductants can plate onto reactors and cause a fire hazard, says Michael J. Krische of the University of Texas at Austin. “You don't want to do ton scale chemistry using elemental zinc or elemental manganese.” Krische and his team, along with collaborators at Genentech, the University of Minnesota Twin Cities, and the University of Pittsburgh, may have come up with a cost-effective solution to the problem.

They’ve unveiled a new coupling method that joins an aryl bromide with an aryl iodide using inexpensive sodium formate as a reductant, along with a commercially available palladium catalyst and an iodide source (Nat. Chem. 2025, DOI: 10.1038/s41557-024-01729-0).

Sodium formate is “so cheap it's even used for deicing runways at airports,” Krische says. His team previously deployed it to put a new spin on other classic reactions, such as the Grignard (J. Am. Chem Soc. 2019, DOI: 10.1021/jacs.8b13652) and Heck couplings (J. Am. Chem. Soc. 2023, DOI: 10.1021/jacs.3c09876) before setting their sights on cross-coupling.

The reaction can also handle coupling partners that don’t work as well with other cross-couplings, such as nitrogen-containing rings. And it works with anilines and aryl boronates, which can be used for subsequent Buchwald-Hartwig and Suzuki-Miyaura reactions, respectively.

Krische says the reaction works best on electron-rich aryl iodides and aryl bromides with an adjacent nitrogen or other heteroatom. The mechanism is also somewhat unusual: the catalyst is a negatively charged complex with two palladium atoms and four iodides. The palladiums cycle between the +1 and +2 oxidation states as they shuffle aryl groups and iodines between the metal centers until the aryl groups are next to each other and can bond together to make the cross-coupled product. “People had never really identified any unique reactivity associated with palladium(I). And this is unique,” Krische says.

Harvard University organic chemist Richard Y. Liu, who was not involved in the project, calls the study “very inspiring work” that “will certainly get a lot of attention from the community.” He adds that the ability to use this reaction in tandem with other coupling methods “really improves its potential for chemical discovery.”

Krische says he and his team will continue working to make the reaction as industry-friendly as possible. For example, they would love to figure out how to make it work with cheaper, greener nickel or cobalt catalysts.

 

Protein catalysts designed to do non-natural chemistry

Researchers couple AI and chemical know-how to create tools for cyclopropanation and silylation reactions

A protein catalyst’s synthetic porphyrin cofactor binds to styrene and a diazo compound, which will form a cyclopropane.

Enzymes are masters of making molecules. They accomplish exquisitely selective chemistry in water, and scientists have used the technique of directed evolution to modify existing enzymes to carry out chemical reactions not found in nature, like creating cyclopropanes and doing silicon-hydrogen bond insertions. Now, researchers have combined artificial intelligence (AI) and their own chemical intuition to create protein catalysts from scratch that can perform these same transformations (Science 2025, DOI: 10.1126/science.adt7268).

AI has become successful at designing proteins, and those who use it to predict and design protein structures have won Nobel Prizes. But chemical know-how is still important, says Yang Yang, a chemistry professor at the University of California, Santa Barbara, who led the project with the University of California, San Francisco’s William F. DeGrado and the University of Pittsburgh’s Peng Liu. “Protein design, even with the best AI-based methods, is not a solved problem. The most efficient way to generate effective designs for catalysis is perhaps to combine the AI-based method and also the in-house experience and knowledge of protein structure,” Yang says.

Compared with enzymes, protein catalysts are simpler, more stable at high temperatures, and can also be used in environmentally friendly organic solvents like ethanol, allowing chemists to load up on organic substrates. In this case, the researchers wanted to create protein catalysts that could do cyclopropanation reactions stereoselectively.

Their first attempts, which primarily relied on AI to design the protein catalysts, had decent stereoselectivity. To create catalysts that built cyclopropanes with an enantiomeric ratio of 99:1, they had to study the structure of their protein catalysts and make adjustments based on their chemical knowledge. The team similarly used directed evolution to improve upon AI-designed protein catalysts for Si–H insertion reactions.

“We think AI tools are definitely very powerful and very transformative. But we do need some additional input from either human expertise or additional chemistry simulation to further enhance the reliability of those AI predictions,” Liu says.

J. L. Ross Anderson, who studies de novo protein design at the University of Bristol and was not involved in the work, calls the project a “tour de force” in terms of combining strategies for creating protein catalysts. He says these new protein catalysts are able to perform particularly tough chemical transformations. “Not only are they challenging just by their very nature but also because of the stereospecificity that they're managing to tap into—it’s another layer of complexity in the design process,” Anderson says.

DeGrado says the new catalysts, which contain either synthetic porphyrin or heme cofactors, could be used instead of expensive metal catalysts to create drug candidates in a medicinal chemistry campaign or when making certain molecules on a large scale.

DeGrado wants other scientists to know that the tools the researchers used are easy to get up and running. “All of these things have gone from being difficult to very fairly simple,” he says. “To me, the impact isn't so much that this was such a difficult thing, but that it was a relatively simple thing that can translate very easily to new labs.”

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