Synthesis of ortho-Diamino-Functionalized 1-Arylnaphthalenes through Nickel-Catalyzed Cyclization of Ynamide-Benzylnitriles with Organoboronic Acids

Intermolecular 1,2-Difunctionalization of Nitriles via Redox Gold Catalysis: Synthesis of Benzoxazoles and Benzimidazoles

The unprecedent gold-catalyzed intermolecular 1,2-difunctionalization of nitriles with o-iodophenols or o-iodoanilines via Au(I)/Au(III) redox catalysis has been developed, providing an expedient route to the synthesis of benzoxazoles or benzimidazoles with broad substrate scope and high functional compatibility. Mechanistic investigation reveals that the Au(III)-Ar species generated via oxidative addition of o-iodophenol to MeDalphosAu+, serves as a key intermediate. Particularly, this annulation is initiated by oxidative addition, rather than the nucleophilic attack of the phenol moiety in o-iodophenol towards the nitrile. The method was also applied to the synthesis of poly aza-heterocycles via a cascade Au(I)/Au(III) and Au(I) catalysis relay.

Access to 2,3-Dihydropyridines Involving Cyano Transformation Relay through Gold Catalysis Assisted by a Lewis Acid

A gold(I)-catalyzed cyclization of enynone-nitriles with amines to 2,3-DHPs assisted by La(OTf)3 has been developed. The compatibility with abundant nucleophiles, high functional group tolerance, rapid assembly of molecular complexity, and late-stage functionalization of bioactive substances make this approach attractive for the construction of 2,3-DHPs, which have rarely been synthesized in the literature. The reaction proceeds via cascade cyclization involving gold/Lewis acid cooperative activation of the alkene and the cyano moiety.

Nickel Catalyzed Selective Arylation of Geminal Dinitriles: Direct Access to α-Cyano Carbonyl Compounds

The catalytic intermolecular arylation of disubstituted geminal dinitriles with in situ generated arylnickel complexes is disclosed. This method efficiently provides various all-carbon substituted α-cyanocarbonyl compounds without additives and an inert atmosphere. It also demonstrates the arylation of R-BINOL and S-BINOL derived geminal dinitriles, preserving optical purity. Mechanistic studies proved that the in situ generated organonickel complex is involved in arylation.

Metal-catalyzed reactions of organic nitriles and boronic acids to access diverse functionality

The nitrile or cyano (-CN) group is one of the most appreciated and effective functional groups in organic synthesis, having a polar unsaturated C-N triple bond. Despite sufficient stability and being intrinsically inert, the nitrile group can be easily transformed into many other functional groups, such as amines, carboxylic acids, ketones, etc. which makes it a vital group in organic synthesis. On the other hand, despite several boronic acids having a low level of genotoxicity, they have found wide applicability in the field of organic synthesis, especially in transition metal-catalyzed cross-coupling reactions. Recently, transition-metal-catalyzed cascade additions or addition/cyclization processes of boronic acids to the nitrile group open up exciting and useful strategies to prepare a variety of functional molecules through the formation of C-C, C-N and CO bonds. Boronic acids can be added to the cyano functionality through catalytic carbometallation or through a radical cascade process to provide newer pathways for the rapid construction of various important acyclic ketones or amides, carbamidines, carbocycles and N,O-heterocycles. The present review focuses on various transition-metal-catalyzed additions of boronic acids via carbometallation or radical cascade processes using the cyano group as an acceptor.