Norrish type II reactions of acyl azolium salts

The photochemical reactivity of acyl azolium salts derived from aliphatic carboxylic acids has been investigated. These species, which serve as models for intermediates generated in N-heterocyclic carbene (NHC) organocatalysis, undergo Norrish type II elimination reactions under irradiation with UVA light in analogy to structurally related aromatic ketones. Moreover, efficient Norrish-Yang cyclization was observed from an adamantyl-substituted derivative. These results further demonstrate the ability of NHCs to influence the absorption properties and photochemical reactivity of carbonyl groups during a catalytic cycle. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The photochemical reactivity of acyl azolium salts derived from aliphatic carboxylic acids was investigated, showing Norris type II elimination reactions and Norris-Yang cyclization under UVA light irradiation. These results demonstrate the influence of NHCs on the absorption properties and photochemical reactivity of carbonyl groups during a catalytic cycle.