Recent Advances in Chemical Modifications of Nitriles

Abstract

Nitrile represents a synthetically important class of compounds, relevant to the preparation of fine organic chemicals, natural products, and biologically active molecules. The electronegative nitrogen atom and electropositive carbon atom of cyano group endow nitriles with rich and diverse chemical properties. Traditional chemical transformations of nitriles usually involve the use of strong acids, bases, and other harsh conditions. To overcome these limitations, various catalytic methods have been explored both in homogeneous and heterogeneous systems. In this review, we summarize some of the recent progress on the development of efficient synthetic methods involving nitriles. Especially, the classic transformations of nitriles including hydration, hydrolysis and reduction reactions are discussed in detail, which provide rapid access to a series of important small molecules, such as amides, ketones, amines, and imines. The reaction development, as well as the design of the catalytic system will be discussed with special emphasis placed on the mechanistic aspects.

Employment of Michael addition reactions for the functionalization of carboranes

“…We first initiated our study by choosing 1-R-substituted o -carboranes (R = C 6 H 5 CH 2 , NO 2 C 6 H 4 , NH 2 C 6 H 4 ) 1–3 as C-nucleophile substrates for Michael cyanoethylation since the cyano group can be easily transformed into carbonyl compounds such as carboxylic acids and amides 31 by hydrolysis or can be converted into amines by reduction. 31 Moreover, the nitrile group in acrylonitrile has the highest electron withdrawing effect 32 and is highly susceptible toward aza-Michael addition reaction.…”

“…We first initiated our study by choosing 1-R-substituted o -carboranes (R = C 6 H 5 CH 2 , NO 2 C 6 H 4 , NH 2 C 6 H 4 ) 1–3 as C-nucleophile substrates for Michael cyanoethylation since the cyano group can be easily transformed into carbonyl compounds such as carboxylic acids and amides 31 by hydrolysis or can be converted into amines by reduction. 31 Moreover, the nitrile group in acrylonitrile has the highest electron withdrawing effect 32 and is highly susceptible toward aza-Michael addition reaction. The reactions of carboranes 1–3 with acrylonitrile ( 4 ) in molar ratio 1 : 1.5 proceeded well in MeCN in the presence of Triton-B (benzyltrimethylammonium hydroxide) as a catalyst (10 mol%) at ambient temperature for 5–7 h affording the corresponding carborane cyanoethyl derivatives 5–7 in 73–81% yields (Scheme 1).…”

Tropylium‐BF4 as Organocatalyst for Efficient Synthesis of Nitriles from Aldoximes; Synthetic Scope and Mechanistic Insights

“…Moreover, the -CN group is a highly versatile synthon that can be converted to a number of other significant functional groups such as amides, amines, aldehydes, and ketones. [1][2][3][4][5] Whereas numerous methods for the synthesis of aromatic and aliphatic nitriles have been developed over the years, [1][2][3][4][5] the quest for the development of new, environmentally more acceptable, cyanide free methods continues. To this end, nitrile synthesis by dehydration of aldoximes has received considerable attention.…”

“…Nitrile groups are widely present in natural products, pharmaceuticals, dyes, and polymers. Moreover, the ‐CN group is a highly versatile synthon that can be converted to a number of other significant functional groups such as amides, amines, aldehydes, and ketones [1–5] . Whereas numerous methods for the synthesis of aromatic and aliphatic nitriles have been developed over the years, [1–5] the quest for the development of new, environmentally more acceptable, cyanide free methods continues.…”

Tropylium tetrafluoroborate promoted hydroboration of nitriles, imines and amides

“…The conversions of nitriles, readily available synthetic precursors, into other N-containing derivatives such as amines, imines or amides are important chemical transformations in both synthetic laboratories and industrial chemistry. 1 This process can be realized by direct hydrogenation or reduction with organometallic or organic hydride donors such as boranes (Scheme 1). 1 a , b The former process often requires precious metal catalysts or stoichiometric amounts of metal hydrides and complicated reaction setups to deliver the desired efficiency and selectivity.…”