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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Scramble-Free Synthesis of Unhindered trans-A2B2-Mesoaryl Porphyrins via Bromophenyl Dipyrromethanes
Muteb H Alshammari1, Sultanah M N Alhunayhin1, David L Hughes1
1School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
Abstract:
Trans-disubstituted porphyrins are highly valuable intermediates across diverse fields, but they pose a significant synthesis challenge in some cases due to scrambling and formation of complex mixtures. Conditions that minimize scrambling also lower yields, but steric hindrance around the meso-aryl substituent can effectively suppress scrambling altogether. Here we report a straightforward approach to valuable trans-A2B2 porphyrin intermediates that are otherwise very difficult to obtain, through use of removable blocking bromide substituents.
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