Light‐Induced CH Arylation of (Hetero)arenes by In Situ Generated Diazo Anhydrides |
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| Authors: | Dr David Cantillo Dr Carlos Mateos Dr Juan A Rincon Dr Oscar de?Frutos Prof?Dr C Oliver Kappe |
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| Affiliation: | 1. Institute of Chemistry, University of Graz, NAWI Graz, Heinrichstrasse 28, 8010 Graz (Austria) http://www.maos.net;2. Centro de Investigación Lilly S. A. Avda. de la Industria 30, 28108 Alcobendas‐Madrid (Spain) |
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| Abstract: | Diazo anhydrides (Ar?N?N?O?N?N?Ar) have been known since 1896 but have rarely been used in synthesis. This communication describes the development of a photochemical catalyst‐free C?H arylation methodology for the preparation of bi(hetero)aryls by the one‐pot reaction of anilines with tert‐butyl nitrite and (hetero)arenes under neutral conditions. The key step in this procedure is the in situ formation and subsequent photochemical (>300 nm) homolytic cleavage of a transient diazo anhydride intermediate. The generated aryl radical then efficiently reacts with a (hetero)arene to form the desired bi(hetero)aryls producing only nitrogen, water, and tert‐butanol as byproducts. The scope of the reaction for several substituted anilines and (hetero)arenes was investigated. A continuous‐flow protocol increasing selectivity and safety has been developed enabling the experimentally straightforward preparation of a variety of substituted bi(hetero)aryls within 45 min of reaction time. |
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| Keywords: | C H arylation continuous‐flow chemistry diazo compounds photochemistry radical chemistry |
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