The tetraalkylammonium-accelerated Norrish-Yang photocyclization of 2-substituted acetophenones

摘要

The tetrabutylammonium-accelerated Norrish-Yang cyclization of 2-ethoxycarbonylmethyloxy- and 2-cyanomethyloxyacetophenones afforded trans-dihydrobenzofuranols in good stereoselectivities through cation-pi interactions between the ammonium and the carbonyl and cyano groups. Furthermore, a new type of organocatalyst possessing both conformation-controlling and triplet-sensitizing units was developed, and was found to be effective in accelerating the Norrish-Yang photocyclization of 2-cyanomethyloxyacetophenone. (C) 2019 Elsevier Ltd. All rights reserved.