Blue LED-Mediated Synthesis of 3-Arylidene Oxindoles

Abstract

Blue LED-promoted cross-coupling olefination of symmetrical and unsymmetrical 3-arylidene oxindoles has been described from diazoindolones and diphenylmethanethiones. Thermal olefin isomerization and stereoselective synthesis of 3-arylidene oxindoles were also demonstrated in good yield.

Visible Light-Induced Reactions of Diazo Compounds and Their Precursors

“…Very recently, Muthusamy's group introduced a photochemical protocol for synthesis of arylidene oxindoles 45.3 from diazoindolones 45.1 and thioketones 45.2 (Scheme 45). 118 The proposed mechanism suggests the formation of sulfonium ylide A, followed by an electrocyclization reaction to produce episulfide B. Subsequently, elemental sulfur is eliminated, furnishing various tetrasubstituted alkenes 45 In an effort to achieve high levels of enantiocontrol for formal [4 + 1] cycloadditions of sulfonium ylides A and ethynylbenzoxazinones 46.2, Lu and co-workers examined a copper-catalyzed approach employing chiral bisoxazoline ligand L* (Scheme 46).…”

“…Very recently, Muthusamy’s group introduced a photochemical protocol for synthesis of arylidene oxindoles 45.3 from diazoindolones 45.1 and thioketones 45.2 (Scheme ). The proposed mechanism suggests the formation of sulfonium ylide A , followed by an electrocyclization reaction to produce episulfide B . Subsequently, elemental sulfur is eliminated, furnishing various tetrasubstituted alkenes 45.3 .…”

Visible photons as ideal reagents for the activation of coloured organic compounds

“…In fact, addition of the carbene (from a diazoindolone) on the sulfur atom of the thione resulted in the formation of a sulphonium ylide that ultimately led to substituted 3-arylidene oxindoles via an electro-cyclization reaction followed by elemental sulfur elimination from the resulting episulfide. 262 All-carbon tetra-substituted olefins were instead formed in moderate to good yields through the visible-light induced coupling between a diazo compound and an iodonium ylide. 263 Moreover, densely substituted itaconimides were easily prepared under solvent-free conditions through a multicomponent reaction by adopting (substituted) pyridines, aryl diazoesters and N-alkylmaleimides as the reaction partners.…”

“…In fact, addition of the carbene (from a diazoindolone) on the sulfur atom of the thione resulted in the formation of a sulphonium ylide that ultimately led to substituted 3-arylidene oxindoles via an electro-cyclization reaction followed by elemental sulfur elimination from the resulting episulfide. 262…”

Visible-Light-Induced Synthesis of Alkylsulfonated Isoquinolinones from 2-Aryl Indoles/Benzimidazoles through Insertion of Sulfur Dioxide

“…One of the most simple and efficient ways to synthesize isoquinolinones is by radical-mediated cascade cyclization of 2-aryl indoles/benzimidazoles derivatives . As a mild and powerful tool, photochemical transformations have been broadly applied to organic radical chemistry . Herein, we propose a photo-induced three-component reaction of HEs, Na 2 S 2 O 5 , and 2-aryl- N -acryloyl indoles/benzimidazoles by using (NH 4 ) 2 S 2 O 8 as the oxidant to achieve the construction of nitrogen-containing fused rings (Scheme ).…”