Visible-Light-Induced Cascade Cyclization of 1-Acryloyl-2-cyanoindole: Access of Difluoroalkylated Pyrrolo[1,2-a]indolediones

Abstract

An effective method for accessing diverse difluoroalkylated pyrrolo­[1,2-a]­indolediones via visible-light-induced PhI­(OAc)2-promoted cascade difluoroalkylation/cyclization reaction under mild conditions has been established. This method is noteworthy for its use of DMSO–H2O as a green medium at room temperature and avoidance of photocatalysts. The reactions are straightforward to execute and convenient to expand on, provide good to excellent yields, and have good functional group tolerance.

Phototriggered Fluoroalkylation/Cyclization of Unactivated 1-Acryloyl-2-cyanoindoles: Synthesis of RCOCF2-Substituted Pyrrolo[1,2-a]indolediones

“…10 Very recently, our group described a convenient method for accessing diverse difluoroalkylated pyrrolo[1,2-a]indolediones via a visible-light-induced PhI(OAc) 2 -promoted cascade difluoroalkylation/cyclization reaction using FeCl 2 as a catalyst (Scheme 1c). 11 Despite the aforementioned works, some efficient synthetic methodologies of functionalized pyrrolo[1,2-a]indolediones have been reported. However, some drawbacks of these strategies are ineluctable, including the use of excess strong oxidant, a long reaction time, and transition-metal catalyst, etc.…”

“…Subsequently, a photocatalyzed persulfate-promoted cascade phosphorylation/cyclization to access various phosphorylated pyrrolo­[1,2- a ]­indolediones was developed by the same group (Scheme b) . Very recently, our group described a convenient method for accessing diverse difluoroalkylated pyrrolo­[1,2- a ]­indolediones via a visible-light-induced PhI­(OAc) 2 -promoted cascade difluoroalkylation/cyclization reaction using FeCl 2 as a catalyst (Scheme c) . Despite the aforementioned works, some efficient synthetic methodologies of functionalized pyrrolo­[1,2- a ]­indolediones have been reported.…”

Photo-induced synthesis of fluoroalkylated quinolinones via an iron-catalyzed LMCT decarboxylation process

“…10 Besides, some other methods have been developed. 11 Although these strategies have made great progress, they still usually depend on harsh reaction conditions, costly metal catalysts or excessive oxidants. Moreover, due to the high oxidation potential of some fluoroalkyl carboxylate anions, decarboxylation reactions are less likely to occur, resulting in a limited selection of fluoroalkyl radical sources.…”

Visible-light-induced photocatalyst-free cascade cyclization of 3-(2-(ethynyl)phenyl)quinazolinones to sulfonated quinolino[2,1-b]quinazolinones

“…Thus, developing efficient and practical procedures for constructing other functionalized quinolino[2,1- b ]quinazolinones still deserves in-depth investigation. Combined with our continued interest in visible-light-catalyzed reactions and heterocyclic synthesis, 8 we herein report a visible-light-driven potassium persulfate (K 2 S 2 O 8 )-promoted cascade cyclization to access various sulfonated quinolino[2,1- b ]quinazolinones using sulfonyl hydrazines as the sulfonyl precursor under a N 2 atmosphere at room temperature (Scheme 1b). The advantages of this reaction include it being transition-metal-free and photocatalyst-free, good functional group compatibility, and mild conditions.…”