Rotational isomerization of 3-substituents in synthetic chlorophyll derivatives

Extra-Annulated Chlorophyll Derivatives by Scholl Reaction

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.

Perspectives on push-pull chromophores derived from click-type [2 + 2] cycloaddition-retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

Various push-pull chromophores can be synthesized in a single and atom-economical step through [2 + 2] cycloaddition-retroelectrocyclization (CA-RE) reactions involving diverse electron-rich alkynes and electron-deficient alkenes. In this review, a comprehensive investigation of the recent and noteworthy advancements in the research on push-pull chromophores prepared via the [2 + 2] CA-RE reaction is conducted. In particular, an overview of the physicochemical properties of the family of these compounds that have been investigated is provided to clarify their potential for future applications.