Catalytic Cyanation of C–N Bonds with CO₂/NH₃

Abstract

Cyanation of benzylic C–N bonds is useful in the preparation of important α-aryl nitriles. The first general catalytic cyanation of α-(hetero)aryl amines, analogous to the Sandmeyer reaction of anilines, was developed using reductive cyanation with CO2/NH3. A broad array of α-aryl nitriles was obtained in high yields and regioselectivity by C–N cleavage of intermediates as ammonium salts. Good tolerance of functional groups such as ethers, CF3, F, Cl, esters, indoles, and benzothiophenes was achieved. Using 13CO2, a 13C-labeled tryptamine homologue (five steps, 31% yield) and Cysmethynil (six steps, 37% yield) were synthesized. Both electronic and steric effects of ligands influence the reactivity of alkyl nickel species with electrophilic silyl isocyanates and thus determine the reactivity and selectivity of the cyanation reaction. This work contributes to the understanding of the controllable activation of CO2/NH3 and provides the promising potential of the amine cyanation reaction in the synthesis of bio-relevant molecules.

Isomorphous Substitution in ZSM-5 in Tandem Methanol/Zeolite Catalysts for the Hydrogenation of CO2 to Aromatics

“…4 Sun et al 5 studied plasma-catalytic CO 2 hydrogenation using Pd/ZnO catalyst to get CO, which is an important intermediate in the Fischer−Tropsch synthesis of hydrocarbon fuels. Cyanation of benzylic C−N bonds is another example of CO 2 utilization studied by Yan et al 6 Some of the largest petrochemical products that are essential to modern life are derived from aromatic chemicals. Currently, more than half of aromatics are sourced from catalytic reforming of crude oil, followed by steam cracking of naphtha.…”

“…Cyanation of benzylic C–N bonds is another example of CO 2 utilization studied by Yan et al. 6 Some of the largest petrochemical products that are essential to modern life are derived from aromatic chemicals. Currently, more than half of aromatics are sourced from catalytic reforming of crude oil, followed by steam cracking of naphtha.…”

Nickel-Catalyzed Inter- and Intramolecular Reductive Cross-Coupling Reactions of Arylbenzylammonium Salts through Highly Site-Selective C–N Bond Cleavage

“… a (a) Reductive cross-coupling reactions of benzyltrimethylammonium salts. − (b) Reductive cross-coupling reactions of aryltrimethylammonium salts. , (c) Highly site-selective C–N bond cleavage for the reductive cross-coupling reactions of arylbenzylammonium salts (this work). …”

“…In recent years, both benzyl and arylammonium salts have been explored as promising electrophiles for reductive cross-coupling reactions. Benzyltrimethylammonium salts have been reported to participate in nickel-catalyzed manganese- or zinc-mediated reductive cross-coupling reactions with CO 2 , , aryl sulfonates, vinyl acetates, and phenyl benzoates (Scheme a) . Yu and co-workers have developed visible-light-driven cross-electrophile couplings of benzyltrimethylammonium salts with aldehydes, ketones, CO 2 , and nitriles in the absence of external reductants.…”

“…Finally, we performed two crossover experiments. The mixture of benzyl(4bromophenyl)ammonium triflate 4b and aryl bromide 2a was subjected to the standard conditions, delivering intermolecular coupling product 3q (59% yield) and intramolecular coupling product 5b (34% yield), together with two byproducts, 4-bromo-N,N-dimethylaniline and N 4 ,N 4 ,N 4 ′,N 4 ′tetramethyl-[1,1′-biphenyl]-4,4′-diamine (Scheme 5b). Moreover, treatment of benzyl(bromoaryl)ammonium triflates 4g and 4n under the standard conditions afforded all of the four possible crossover products 5a, 5g, 5n, and 5r.…”