The Renaissance of Organo Nitriles in Organic Synthesis

Abstract

In the arena of functional group-oriented organic synthesis, 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 reactivities. 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 dienes allow the synthesis of many important carbo-and heterocycles. Furthermore, the nitrile serves as a directing group in many CÀ H bond functionalization reactions to introduce diverse functionalities 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 CÀ 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.

Visible-Light-Mediated Solvent-Switched Photosensitizer-Free Synthesis of Polyfunctionalized Quinolines and Pyridines

“…A similar [2 + 2 + 2] cycloaddition of α,ω-diynes with nitriles using Ir­(I)-catalyzed is reported by the Takeuchi group to access pyridines [Scheme (iv)] . Taking cues from the literature, we envisaged that the cascade addition/cyclization of nitrile functionality under metal or metal-free conditions would lead to the formation of N -heterocycles. , …”

“…Lately, the nitrile-triggered reactions have gained immense importance in serving as acceptors, which, in combination with a suitable nucleophilic partner, leads to carbocycles and heterocycles . Furthermore, nitrile-triggered C–H functionalization is an emerging area due to its flexibility and sustainability in organic transformation.…”

“…Furthermore, nitrile-triggered C–H functionalization is an emerging area due to its flexibility and sustainability in organic transformation. In this method, a metal (M) is inserted into the C–H bond by coordinating with the nitrile through chelation with the metal center thereby forming a C–M species, which takes part in many coupling reactions . Some of these transformations provide access to functionalize quinolines and pyridines via the formation of C–C and C–N bonds.…”

Electrohydrogenation of Nitriles with Amines by Cobalt Catalysis

“…[16] However, the inert of C�N triple bond makes it less reactive and difficult to reduce, and a high negative reductive potential is required. [17] Additionally, the selectivity control of nitrile reduction remains challenging owing to the formation of primary, secondary, and tertiary amine product mixtures. [18] In addition to widely explored primary amines, [18e] the selective synthesis of diverse secondary and tertiary amines, especially by cross hydrogenative coupling with an additional amine substrate constitutes a particular challenge.…”

Nucleophile-Controlled Trapping of Gold Carbene by Nitriles and Water: Synthesis of 5H-Pyrimido[5,4-b]indoles and 2-Benzylidene-3-indolinones

“…Nitriles are versatile synthetic precursors and can participate in transition-metal-catalyzed alkyne insertion and annulations, cycloadditions, and nucleophilic or radical cascade addition/cyclizations to provide various heterocycles . The common nucleophilic nitriles have been reported as C 2 synthons with various types of gold carbene intermediates for [3 + 2]-annulation reactions, which can generate a series of substituted oxazoles .…”