A metal-free benzannulation of diazo compounds under visible light irradiation was developed. The photocatalytic single electron transfer by Hantzsch ester to the diazo enolates results into enolate vinyl radicals, which were trapped by alkynes leading to functionalized naphthalene-1-ols. The enolate vinyl radicals were also trapped intramolecularly by o-aryl groups to access phenanthren-10-ols. The wide substrate scope and mild conditions employing inexpensive Hantzsch ester as photosensitizer are noteworthy attributes of the reaction.
Am ild ande fficient photocatalytic protocol for the synthesis of 3-aryl-2-difluoroacetyl indenones has been established. The reaction sequence involvesv isible-light-catalyzed difluoroacetylation of 1,3-diarylpropynones followed by intramolecular radicalc yclization.T he reaction exhibits high regioselectivity and good functional group tolerance. This is asimple method for the introductionofadifluoroalkyl group in the indenone scaffold, which is valuablef rom the point of view of medicinal chemistry.
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