Electrochemical NH-Sulfoximidation with α-Keto Acids

An electrochemical N-acylation of sulfoximine has been achieved via the coupling of α-keto acids and NH-sulfoximines. This process involves the sequential cleavage of C-C bond followed by C(sp2)-N bond formation, with the liberation of H2 and CO2 as the by-products. A library of N-aroylated sulfoximines is produced via the coupling of aroyl and sulfoximidoyl radicals by anodic oxidation under constant current electrolysis (CCE). The compatibility of the present protocol has been demonstrated by coupling of various bio-active compounds, such as NH-sulfoximine derived from (-)-borneol, L-menthol, D-glucose derivative, and some commercial drugs such as flurbiprofen, and ibuprofen. This late-stage functionalization highlights the importance of this sustainable protocol. Besides this, various control experiments and detection of H2 evolution have been performed to support the proposed mechanism.

Photocatalytic radical cyclization of N-(o-cyanobiaryl)acrylamides with oxime esters

A visible-light-mediated radical cascade cyclization of N-(o-cyanobiaryl)acrylamides with oxime esters for the assembly of acyl-containing pyrido[4,3,2-gh]phenanthridines has been developed. The present protocol tolerates a wide range of oxime esters through a single reaction via fragmentation, radical addition, nitrile insertion, and cyclization under mild conditions.

Oxidative cascade cyclization of N-arylacrylamides with TMSN3

An azido-radical-triggered cyclization of N-(o-cyanobiaryl)acrylamides with TMSN3via a C(sp3)-N/C(sp2)-C(sp3)/C(sp2)-N bond formation cascade is described. This reaction features mild conditions and high bond-forming efficiency, making it an efficient method for the construction of azide-substituted pyridophenanthridines.

Metal- and Base-Free Radical Cascade Cyclization/Hydrolysis of CN-Containing 1,6-Enynes with Ethers to Access Polyheterocycles

A convenient and straightforward approach for the radical cascade cyclization/hydrolysis of CN-containing 1,6-enynes with simple ethers under metal- and base-free conditions is described. This strategy provides a variety of valuable ethers-substituted polyheterocycles via the construction of three C-C bonds, one C=O bond, and two new six-membered rings within a single procedure. The resulting products can smoothly undergo follow-up conversions to various useful scaffolds. The methodology shows excellent functional group tolerance, high step- and atom- economy, and mild reaction conditions, which can be further scaled up to gram quantity in a satisfactory yield.

The Renaissance of Organo Nitriles in Organic Synthesis

In the arena of functional group-oriented organic synthesis, the nitrile or cyano functionality is of immense importance. The presence of nucleophilic N -atom, π-coordinating ability of the triple bond, and electrophilic C-center imparts unique and interesting reactivity. Owing to the ability of the nitrile to transform into various other functional groups or intermediates, the chemistry is very rich and diverse. In particular, the involvement of nitrile in numerous organic reactions such as inter- or intramolecular alkyne insertion, [2 + 2 + 2] cycloaddition with alkynes, [3 + 2] cycloaddition with azides, [4 + 2] cycloaddition with diene allow the synthesis of many important carbocycles and heterocycles. Furthermore, the nitrile serves as a directing group in many C-H bond functionalization reactions to introduce diverse functionality and participate as a radical acceptor in radical cascade strategies to obtain a large variety of functional molecules. This review mainly focuses on the reactivity and diverse synthetic application of the nitrile including C-H bond functionalization, alkyne insertion, cycloaddition, and thermal or photochemical cascade strategy. The objective of the current review aims at bringing out the striking collection of various nitrile-triggered organic transformations.

K2S2O8-mediated acylarylation of unactivated alkenes via acyl radical addition/C–H annulation cascade of N-allyl-indoles with silver cocatalysis

A silver-catalyzed, K2S2O8-mediated protocol to access the regioselective acylarylation of unactivated alkenes was reported.

Acyl Radicals from α-Keto Acids: Metal-Free Visible-Light-Promoted Acylation of Heterocycles

A general and metal-free visible-light-induced decarboxylative arylation procedure at room temperature was described for the construction of acylated heterocyclic derivatives, such as benzimidazo/indolo[2,1-a]isoquinolin-6(5H)-ones, aroylazaspiro[4.5]trienones, thioflavones, and so on. This practical arylation procedure was conducted by using 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) as a photocatalyst under mild conditions, which avoided the use of an additional base, traditional heating, and metal reagents.

Nitriles as radical acceptors in radical cascade reactions

The application of the cyano group as a radical acceptor in the cascade reactions for the construction of various important heterocycles and carbocycles was summarized.

Visible light induced radical cascade cyclization of ortho-cyanoarylacrylamides with phosphine oxides for the preparation of phosphorylated quinoline-2,4(1H,3H)-dione

Visible light induced cascade cyclization of ortho-cyanoarylacrylamides with phosphine oxides for the preparation of phosphorylated quinoline-2,4(1H,3H)-dione was presented. Products with moderate to good yields were efficiently isolated.

Oxidative cascade cyclization of 2-cyano-3-arylaniline derived acrylamides with toluenes, ethers, aliphatic alcohols or simple alkanes

Oxidative radical cascade cyclization of 2-cyano-3-arylaniline derived acrylamides with a variety of hydrocarbons including toluenes, ethers, aliphatic alcohols and alkanes has been developed to construct alkyl substituted pyridophenanthridines.

Metal-free benzoylation of imidazoheterocycles by oxidative decarboxylation of arylglyoxylic acids

A simple and straightforward approach has been realized for the direct benzoylation of imidazoheterocycles by oxidative decarboxylation of arylglyoxylic acids in the presence of K₂S₂O₈ as an oxidant.