The Ionic Auxiliary Concept in Solid State Organic Photochemistry

5.06 Di-π-methane, Oxa-di-π-methane, and Aza-di-π-methane Photoisomerization

“…57 Irradiation of chiral salts is an alternative and more general approach to obtain enantiopure compounds via solid-state photochemistry. 58 Cocrystallization with a chiral molecule is another method to induce chirality in the di-p-methane photoisomerization. 59 Recently, the reaction was also carried out in other chiral media such as chiral mesoporous silica 60,102 or ionic liquids.…”

Enantiocontrolled solid-state photodimerizations via a chiral sulfonamidecinnamic acid

“…In conclusion, we have successfully organized pairs of 'fish hook' shaped molecules into supramolecular dimers that persist despite the use of racemic (1), quasiracemic (2), and one-component homochiral (3) molecular scaffolds. This approach provides a powerful structural tool to align adjacent olefinic groups with <3.8 Å separation for UV initiated quantitative single-crystal-to-single-crystal transformations.…”

Supramolecular photochemistry in zeolites: From catalysts to sunscreens

“…A much more general strategy developed by Scheffer et al encourages the crystallization of achiral molecules into chiral space groups by forming a crystalline salt between a prochiral carboxylic acid-containing reactant and an optically pure, inert amine. This is called the "ionic chiral auxiliary approach" [131,132]. This methodology has lead to excellent optical yields in a wide variety of photochemical reactions, ranging from di-π-methane rearrangements to Yang photocyclization reactions [132].…”