Visible‐light‐catalyzed Tandem Difluoroacetylation–Intramolecular Cyclization of 1,3‐Diarylpropynones: Access to Difluoroacetylated Indenones

Abstract

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.

Visible light promoted difunctionalization reactions of alkynes

“…Synthesis of 3-difluoro acetylated coumarins from phenyl alkynoates and 2-bromo-2,2-difluoroacetate could be realized by employing fac-Ir(ppy)3 as a catalyst and potassium carbonate as a base under irradiation by blue LEDs. Similar strategies were used for the syntheses of 3-aryl-2-difluoroacetyl indenones [75,76] and 3-difluoro acetylated quinolines [77]. In addition, Kuang and Wu achieved a vinyl difluoroalkylation and aminosulfonylation of alkynes with 2-bromo-2,2-difluoroacetate [78].…”

Promising reagents for difluoroalkylation

“…A mild and efficient photocatalytic protocol for the synthesis of difluoroacetylindenones via the reaction of 1,3-diarylpropynones with ethyl bromodifluoroacetate was established by Rastogi and coworkers (Scheme 61). 137 The visible-light-catalyzed difluoroacetylation of 1,3-diarylpropynones followed by intramolecular radical cyclization was proposed for this reaction.…”

Visible‐Light‐Promoted Oxy‐difluoroalkylation of Aryl Alkynes for the Synthesis of β‐Fluoroenones and α‐Difluoroalkyl Ketones

“…As an efficient building block, alkynes have attracted considerable attentions to construct multiple functional groups. [11] So far, previous researches mainly focused on the carbo-difluoroalkylation of alkynes for preparation of carbon [12] and hetero cyclic compounds [13] via cascade difluoroalkylation/radical cyclization.…”