Imuta T, Hara N, Ogasawara S, Tamiaki H. Extra-Annulated Chlorophyll Derivatives by Scholl Reaction.
Org Lett 2024;
26:6259-6262. [PMID:
39018048 DOI:
10.1021/acs.orglett.4c02238]
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Abstract
The ferric chloride assisted Scholl reaction of methyl (3,5-dimethoxyphenyl)carbonyl-pyropheophorbide-a produced an extra-annulated, didehydrogenated chlorophyll derivative with a six-membered ring fused at the pyrrole A-ring. The steric interaction of the substituents on the additional tetralone and B-rings induced molecular helicity. The helically cyclized stereoisomers were separated by recrystallization, and their (P/M)-stereochemistry was confirmed by circular dichroism spectra. The distortion of their chlorin π-systems broadened electronic absorption bands to cover all visible regions and reach the near-infrared region.
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