Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water

Abstract

Unprecedented light-induced oxidant and metal-free tandem radical cyclization–trifluoromethylation and dehydrogenative oxygenation of 1,6-enynes have been achieved using a photoredox catalyst, CF3SO2Na, and water as the oxygen source.

Recent Advances in Radical‐Enabled Bicyclization and Annulation/1,n‐Bifunctionalization Reactions

“…Almost at the same time, the Kumar group developed an almost-identical version of this reaction in conjunction with inexpensive and practical phenanthrene-9,10-dione as a photoredox catalyst. [61] In comparison with Jiang and co-workers' method, this visible-light-induced radicalc yclization/1,7oxytrifluoromethylation reactiono f1 ,6-enynes featured oxidant-and metal-free conditions (Scheme 38 a). Mechanistic in-Scheme37.…”

Synthesis of Cyclic Compounds via Photoinduced Radical Cyclization Cascade of C=C bonds

“…Apart from the above frequently used substrates, 1,n‐enynes also attracted attention as highly effective radical acceptors for the construction of cyclic scaffolds via cascade cyclization reaction. In 2017, Kumar reported an unprecedented visible‐light‐induced dehydrogenative cascade trifluoromethylation and oxidation of 1,6‐enynes in the absence of oxidant and transition‐metal, which provided a facile access to various CF 3 ‐containing C 3 ‐aryloyl/acylated benzofurans, benzothiophenes and indoles (Scheme ) . Broad substrate scope of this protocol was demonstrated with a large number of phenolic, thiophenolic and anilinic 1,6‐enynes.…”

Palladium‐catalyzed cyclization reaction of N‐(2‐Haloaryl)alkynylimines: Synthesis of 3‐acylindoles using water as the sole solvent and oxygen source

“…In the past few years, the direct 3‐acylation of indoles has been developed, and is well synthetic procedures of 3‐acylindoles . On the other hand, direct construction of the 3‐acylindole skeleton from acyclic precursors has also got considerable attention, and some significant approaches have been achieved, such as intramolecular cyclization of enaminones, direct intramolecular oxidative coupling or radical cyclization of aminoalkynes, Rh‐catalyzed annulation of N‐phenylamidines with α‐Cl ketones, Ru‐ or Rh‐catalyzed selective C‐H activation/annulation of imidamides and sulfoxonium ylides, iodine‐mediated tandem aza ‐michael addition/C‐H functionalization of aniline and α,β‐ynones, copper‐catalyzed cyclization of N ‐(2‐iodoaryl)enaminones, visible light induced intramolecular radical cyclization of N ‐[2‐(alkynyl)phenyl]trifluoroacetimidoyl chlorides, Pd‐catalyzed isocyanide insertion and oxypalladation of alkyne, visible‐light‐induced oxidant and metal‐free dehydrogenative cascade trifluoromethylation and oxidation of 1,6‐enynes with water, as well as palladium‐catalyzed cyclization reaction of N ‐( o ‐haloaryl)alkynylimines producing 2‐trifluoromethylindole derivatives . From the perspective of green chemistry, water is an ideal solvent since it is a non‐toxic, abundant, cost‐effective and environmental‐friendly solvent .…”