Aluminum Redox Catalysis: Cyclotrimerization of Alkynes

Aluminum Redox Catalysis: Reppe Cyclotrimerization of Alkynes | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Aluminum Redox Catalysis: Reppe Cyclotrimerization of Alkynes Xin Zhang, Liu Leo Liu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5825959/v2 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 11 Feb, 2026 Read the published version in Nature → Version 2 posted You are reading this latest preprint version Show more versions Abstract Aluminum, as the third most abundant element comprising over 8% of the Earth's crust, is the most prevalent metallic constituent in nature. 1 Historically, aluminum catalysis has predominantly exploited the inherent Lewis acidity associated with its stable +III oxidation state. 2 Due to its uniquely low electronegativity (1.61)—the lowest among p-block elements—and the absence of an inert pair effect, aluminum presents formidable intrinsic challenges for engaging in catalytic redox transformations. Herein, we disclose the unprecedented redox catalytic capability of a low-valent aluminum species, carbazolylaluminylene, 3 which executes a complete Al(I)/Al(III) catalytic cycle encompassing oxidative addition, double insertion, intramolecular isomerization, and reductive elimination — fundamental mechanistic steps conventionally exclusive to transition metal catalysis. Leveraging this Al(I)/Al(III) redox cycle, we achieve highly efficient and regioselective Reppe cyclotrimerization of alkynes, 4, 5 producing diverse benzene derivatives with a turnover number of up to 2290. Through X-ray crystallographic and quantum chemical analyses, we elucidate how the dynamic nitrogen geometry within the carbazolyl ligand framework precisely modulates the aluminum coordination environment, thereby facilitating the catalytic cycle. This work not only fundamentally advances the conceptual understanding of main-group redox catalysis but also sets a compelling precedent for future catalyst design and sustainable synthetic methodologies centered around aluminum redox transformations. Aluminum Catalysis Alkynes Mechanism Full Text Additional Declarations The authors declare no competing interests. Supplementary Files SupplementaryInformation.pdf SI Cite Share Download PDF Status: Published Journal Publication published 11 Feb, 2026 Read the published version in Nature → Version 2 posted You are reading this latest preprint version Show more versions Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5825959","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":402828068,"identity":"3fb6f04d-09b1-44da-99b1-2f2dfb782d8f","order_by":0,"name":"Xin Zhang","email":"","orcid":"","institution":"SUSTech","correspondingAuthor":false,"prefix":"","firstName":"Xin","middleName":"","lastName":"Zhang","suffix":""},{"id":402828069,"identity":"7c667b91-7004-4b92-9b46-eb7ab1786cc0","order_by":1,"name":"Liu Leo 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Herein, we disclose the unprecedented redox catalytic capability of a low-valent aluminum species, carbazolylaluminylene,\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e which executes a complete Al(I)/Al(III) catalytic cycle encompassing oxidative addition, double insertion, intramolecular isomerization, and reductive elimination\u003c/strong\u003e—\u003cstrong\u003efundamental mechanistic steps conventionally exclusive to transition metal catalysis. Leveraging this Al(I)/Al(III) redox cycle, we achieve highly efficient and regioselective Reppe cyclotrimerization of alkynes,\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e4, 5\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e producing diverse benzene derivatives with a turnover number of up to 2290. 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