m‐Pyrenisubporphyrins and Their BIII Complexes and Reduced Congeners

Abstract m ‐Pyrenisubporphyrins were synthesized by Pd‐catalyzed cross‐coupling of α , α ’‐diboryl‐ m ‐pyrenitripyrrane with 9,10‐bis(1,1‐dibromomethylenyl)anthracene followed by oxidation with DDQ. Reaction of the m ‐pyrenisubporphyrin with BBr 3 and triethylamine gave a B‐hydroxy complex and an oxygen‐atom‐inserted product. Reaction of the m ‐pyrenisubporphyrin with PhBCl 2 and triethylamine gave a B‐phenyl complex. These m ‐pyrenisubporphyrins show red‐shifted absorption bands, reflecting the incorporated pyrene segment, but are all nonaromatic. Reduction of m ‐pyrenisubporphyrin with p ‐tosylhydrazide and K 2 CO 3 gave m ‐pyrenisubchlorin and m ‐pyrenisubbacteriochlorin, depending upon the reaction conditions. These reduced products have also been shown to be nonaromatic by the low‐field shifted chemical shifts of the inner pyrrolic protons, broad and non‐structured absorption bands, and small NICS values.