Visible Light-Mediated Photochemical Reactions of 2-(2'-Alkenyloxy)cycloalk-2-enones.

ABSTRACT: The title compounds were prepared, and their reactivity was studied upon sensitized irradiation at λ = 420 nm. Thioxanthen-9-one was employed as the sensitizer at a loading of 10 mol % in small-scale reactions and of 2.5 mol % on a larger scale. Cyclohex-2-enones substituted by a 2'-propenyloxy, 2'-butenyloxy, 2'-pentenyloxy, or 2'-methyl-2'-propenyloxy group in the 2-position gave the products of an intramolecular [2 + 2] photocycloadditon. The reaction proceeded with high regioselectivity (crossed product) and perfect diastereoselectivity (nine examples, 34-99% yield). If the olefin in the tether was trisubstituted (3'-methyl-2'-butenyloxy), no cycloaddition was observed. Rather, a cyclization with subsequent hydrogen abstraction occurred (three examples, 65-86% yield). The results are c

SUBMITTER: Graßl R 

PROVIDER: S-EPMC7476038 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature