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Synthesis of Redshifted Azobenzene Photoswitches by Late‐Stage Functionalization
Author(s) -
Konrad David B.,
Frank James A.,
Trauner Dirk
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201505061
Subject(s) - azobenzene , surface modification , visible spectrum , isomerization , tetra , photochemistry , materials science , photoisomerization , substrate (aquarium) , chemistry , nanotechnology , combinatorial chemistry , optoelectronics , catalysis , polymer , organic chemistry , medicinal chemistry , oceanography , geology
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.