Visible light-mediated radical-cascade addition/cyclization of arylacrylamides with aldehydes to form quaternary oxindoles at room temperature

Abstract

A visible-light-mediated oxidative cyclization of N-arylacrylamides by a radical cascade with readily available aliphatic or aromatic aldehydes was achieved. The transformation provides an operational, mild, and efficient access to various...

NaI/PPh3-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

“…In summary, we developed an effective photocatalytic decarboxylative radical cascade cyclization of N -arylacrylamides with various redox-active esters derived from common and/or important carboxylic acids under mild conditions. Complementary to traditional transition metal photocatalysis and organo-photocatalysis [ 85 ], the readily available and inexpensive NaI/PPh 3 can operate as an efficient photoredox catalyst, providing an economical access to construct important oxindole scaffolds containing a quaternary carbon center. This synthetic method features a broad substrate scope, good functional group tolerance and operational simplicity.…”

Visible‐Light‐Induced Acylation/Arylation of Alkenes via Aryl Migration/Desulfonylation

“…With the development of photoredox catalysis, [3] visible‐light catalysis provides a powerful platform to achieve the acyl radical generation from corresponding precursors in a mild and environmentally friendly path. A variety of acyl radical precursors including acyl selenide, [2] aroyl chlorides, [4] aryl anhydrides, [5] acylsilanes, [6] 2‐pyridylthioesters, [7] carboxylic acid, [8a–f] and aldehyde [8g] could be converted to acyl radical species through direct cleavage of C(O)−X (X=Se, Cl, OCOR, Si, S, OH, H, etc .) bond through single electron transfer (SET) in the presence of the photocatalysis, and both aryl‐ and alkyl‐substituted acyl groups could be efficiently transferred to generate acylated products.…”

Pd-Catalyzed Photochemical Alkylative Functionalization of C═C and C═N Bonds

“…Among the known methods, those that employ functionalized precursors to deliver an alkyl group are the most prevalent. Alkylboranes are widely used for alkylation assisted by transition metals or strong oxidants. , The N -hydroxy phthalimide esters are alternative alkylating reagents formed by the combination of NHPI and the corresponding carboxylic acids. − Other reagents include alkylated dihydropyridines (DHPs) − and Katritzky salts. − Decarboxylative alkylation with corresponding carboxylic acids − and decarbonylative alkylation − with aldehydes are also well-explored. The development of alkylation strategies that do not require pre-functionalized precursors, harsh oxidizing conditions, or expensive/highly engineered photocatalysts represents an advancement in this area.…”