Boron Arylations of Subporphyrins with Aryl Zinc Reagents

Abstract

Abstract Boron arylations of B‐ (methoxo)triphenylsubporphyrin have been developed with a combined use of ArZnI⋅LiCl and trimethylsilyl chloride. Aryl zinc reagents bearing bromo, cyano, amide, and ester groups can be employed for the B ‐arylation reaction to provide the corresponding B ‐arylated subporphyrins in moderate yields. Postmodifications of B ‐arylated subporphyrins have been demonstrated without loss of the B−C bond. These modifications include conversion of the cyano group into a benzoyl group with PhMgBr, hydrolysis of the ester group to give B ‐(4‐carboxyphenyl)subporphyrin, and Pd‐catalyzed Suzuki–Miyaura coupling of the 4‐bromophenyl group to give a 1,4‐phenylene‐bridged subporphyrin–Zn II porphyrin hybrid that displays intramolecular excitation energy transfer from the subporphyrin to the porphyrin. The newly synthesized B ‐arylated subporphyrins have been fully characterized by NMR, UV/Vis absorption and fluorescence spectroscopies, mass spectrometry, electrochemical measurements, and X‐ray diffraction analysis.