Synthesis of Redshifted Azobenzene Photoswitches by Late‐Stage Functionalization |
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| Authors: | David B Konrad James A Frank Prof Dr Dirk Trauner |
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| Affiliation: | Department of Chemistry, Ludwig-Maximilians-Universit?t München, Munich, Germany |
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| Abstract: | Azobenzenes are versatile photoswitches that can be cycled between their trans‐ and cis‐configuration with light. The wavelengths required for this isomerization are substantially shifted from the UV to the visible range through tetra‐ortho‐chlorination. These halogenated azobenzenes display unique photoswitching characteristics, but their syntheses remain limited and inefficient. A new general method for the synthesis of tetra‐ortho‐chloro azobenzenes has been developed, which relies on direct palladium(II)‐catalyzed C?H activation of pre‐existing standard azobenzenes. This late‐stage functionalization has a broad substrate scope and can be used to create a variety of useful building blocks for the construction of more elaborate redshifted photopharmaceuticals. This method is used to prepare red‐ AzCA‐4 , a photoswitchable vanilloid that enables optical control of the cation channel TRPV1 with visible light. |
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| Keywords: | azobenzene C− H activation halogenation ion channels photopharmacology |
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