Introduction of a Third Meso Substituent into 5,10-Diaryl Chlorins and Oxochlorins

摘要

Chlorins/oxochlorins bearing distinct patterns'of substituents are valuable compounds in bioorganic and materials chemistry.Treatment of a 5,10-diaryl-substituted chlorin or oxochlorin with TFA-di resulted in selective deuteriation of the remaining meso positions(15,20)rather than any of the beta-pyrrolic positions.Electrophilic iodination or bromination of a 5,10-diaryl-substituted chlorin proceeded with high regioselectivity,affording the 5,10-diaryl-15-halo-substituted chlorin.Iodination or bromination of a free base 5,10-diaryloxochlorin gave a mixture of products arising through halogenation at the 15-,20-,and beta-pyrrolic positions,while bromination of a zinc 5,10-diaryloxochlorin selectively gave the 5,10-diaryl-20-bromo-substituted oxochlorin.The Suzuki coupling reaction of a phenyl boronic acid derivative and a 5,10-diaryl-15-iodooxochlorin or 5,10-diaryl-20-bromooxochlorin gave the corresponding 5,10,15-or 5,10,20-triaryloxochlorin.The introduction of a third aryl substituent into the chlorin or oxochlorin causes an approx5-nm red shift of the long wavelength Q_y absorption band.Two phenylethyne-linked oxochlorin-oxochlorin dyads in distinct metalation states(zinc/free bas'e,free base/zinc)were prepared by Sonogashira coupling reactions of a 5,10-diaryl-20-bromooxochlorin and a 10-substituted ethynylphenyl oxochlorin.This study provides access to new chlorins/oxochlorins that can be utilized in diverse applications.