Visible Light Photoredox-Catalyzed α-Alkylation of Cyclic Tertiary Arylamines

Abstract

An efficient method was successfully developed to obtain cyclic β-amino ketones via visible-light photoredox catalysis. With this catalytic system, vinyl azides and N-Ph pyrrolidines react to form cyclic β-amino ketones by α-amino radical addition. This method provides a simple, mild, straightforward, and novel paradigm to prepare important β-amino ketones.

Vinyl Azides as Radical Acceptors in the Vitamin B12-Catalyzed Synthesis of Unsymmetrical Ketones

“… 7 This process is radical in nature and proceeds via a chain mechanism involving iminyl radicals as intermediates. Other radical sources have been shown to be suitable for reaction with vinyl azides; these include pyrrolidines, 8 carboxylic acids, 9 trifluoromethanesulfonates, 10 and thiols. 11 …”

“…Xu and co-workers prepared β-amino-ketones from N -Ph-pyrrolidines and vinyl azides. 8 The Nevado group reported a Ag(I)-promoted synthesis of cyclic ketones involving alkyl radicals generated from carboxylic acids. 18 While investigating the mechanism of azidoalkylation of alkenes with diazoacetate, the Doyle group proposed that the addition of α-ester radicals to vinyl azides, followed by denitrogenative fragmentation and hydrolysis, afforded ketones in 47% yield.…”

“…Vinyl azides have recently emerged as effective radical acceptors. Xu and co-workers prepared β-amino-ketones from N -Ph-pyrrolidines and vinyl azides . The Nevado group reported a Ag­(I)-promoted synthesis of cyclic ketones involving alkyl radicals generated from carboxylic acids .…”

Norhygrine Alkaloid and Its Derivatives: Synthetic Approaches and Applications to the Natural Products Synthesis

“…The proposed method is distinguished by simplicity, mild reaction conditions, what allows one to obtain large series of compounds (Scheme 6b). [38,39] When N-substituted pyrrolidines 24 react with cinnamic acid 25 derivatives in the presence of nickel(II) acetate, 1-aryl-2-(pyrrolidin-2-yl)ethan-1ones 26 are formed (Scheme 6,c). [40] The synthesis of d).…”

CuCl2·2H2O/TBHP mediated synthesis of β-enaminones via coupling reaction of vinyl azides with aldehydes

“…α-Arylvinylazide, bearing conjugated azide and alkene functional groups, are an important class of functionalized alkenes and have been recognized as versatile and fascinating building blocks in organic synthesis due to their multifaceted reactivity. 19 Recently, radical cross coupling of vinyl azides have attracted considerable attention from chemists, especially vinyl azide derivatives are employed as radical acceptors to construct various molecular skeletons, such as spiroamines, 20 phenanthridines and quinoxalines, 21 O-phthalimide oximes, 22 gem-bisarylthio enamines, 23 β-keto sulfones, 24 β-enamino sulfones, 18a,25 β-amino ketones, 26 β-enaminones 18 and so on. 27 Based on our and other groups' previous studies on vinyl azides, it is believed that iminyl radical intermediate could be produced after the addition of aldehydes derived acyl radical with the terminal carbon atom of the CvC bond of vinyl azide to form C-C bond, and subsequently recombination of iminyl radical with acyl radical may take place to form C-N bond.…”