Unsaturated nitriles: conjugate additions of carbon nucleophiles to a recalcitrant class of acceptors

Crystal structure of 2-(2,4-diphenyl-3-aza-bicyclo-[3.3.1]nonan-9-yl-idene)aceto-nitrile

In the title 3-aza-bicyclo-nonane derivative, C22H22N2, both the fused piperidine and cyclo-hexane rings adopt a chair conformation. The phenyl rings attached to the central aza-bicylononane fragment in an equatorial orientation are inclined to each other at 23.7 (1)°. The amino group is not involved in any hydrogen bonding, so the crystal packing is stabilized only by van der Waals forces.

Copper-catalyzed direct transformation of simple alkynes to alkenyl nitriles via aerobic oxidative N-incorporation

A novel Cu-catalyzed aerobic oxidative N-incorporation into aliphatic terminal alkynes for the synthesis of alkenyl nitriles has been reported. The usage of inexpensive copper catalyst, O₂ as the sole oxidant, broad substrate scope as well as the feasibility for “the late-stage modification” make this protocol very promising.

A novel direct transformation of aliphatic terminal alkynes to alkenyl nitriles through the incorporation of a nitrogen atom into the simple hydrocarbons has been reported. The usage of inexpensive copper catalyst, O₂ as the sole oxidant, broad substrate scope as well as feasibility for “late-stage modification” make this protocol very promising. Mechanistic studies including DFT calculation demonstrate a novel 1,2-hydride shift process for this novel nitrogenation reaction.

Straightforward synthesis of 1,2-dicyanoalkanes from nitroalkenes and silyl cyanide mediated by tetrabutylammonium fluoride

A straightforward synthesis of 1,2-dicyanoalkanes by reacting nitroalkenes with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride is described. The reaction proceeds through a tandem double Michael addition under mild conditions. Employing the hypervalent silicate generated from trimethylsilyl cyanide and tetrabutylammonium fluoride is essential for achieving this transformation. Mechanistic studies suggest that a small amount of water included in the reaction media plays a key role. This protocol is applicable to various types of substrates including electron-rich and electron-deficient aromatic nitroalkenes, and aliphatic nitroalkenes. Moreover, vinyl sulfones were found to be good alternatives, particularly for electron-deficient nitroalkenes. The broad substrate scope and functional group tolerance of the reaction makes this approach a practical method for the synthesis of valuable 1,2-dicyanoalkanes.

Oxidative C(sp3)–H functionalization of acetonitrile and alkanes with allylic alcohols under metal-free conditions

Direct oxidative C(sp³)–H functionalization of acetonitrile and alkanes with α,α-diaryl allylic alcohols has been developed.

Copper-catalyzed cyanation of aryl iodides with α-cyanoacetates via C–CN bond activation

A mild copper-catalyzed cyanation of aryl iodides using readily available and friendly α-cyanoacetates as the CN source is reported.

Synthesis of nitriles via palladium-catalyzed water shuffling from amides to acetonitrile

Palladium-catalyzed synthesis of nitriles from amides has been described. Two similar, but complementary reaction conditions have been identified to convert various amides including α,β,γ,δ-unsaturated amides, cinnamides, aromatic amides and alkyl amides to the corresponding nitriles in good to excellent yield.

Palladium-catalyzed direct addition of 2-aminobenzonitriles to sodium arylsulfinates: synthesis of o-aminobenzophenones

The first example of the palladium-catalyzed synthesis of o-aminobenzophenones in moderate to excellent yields via a direct addition of sodium arylsulfinates to unprotected 2-aminobenzonitriles was reported. A plausible mechanism for the formation of o-aminobenzophenones involving desulfination and addition reactions was proposed. The utility of this transformation was demonstrated by its compatibility with a wide range of functional groups. Thus, the method represents a convenient and practical strategy for synthesis of o-aminobenzophenones.

Predicting the reactivity of nitrile-carrying compounds with cysteine: a combined computational and experimental study

Here, we report on a mechanistic investigation based on DFT calculations and kinetic measures aimed at determining the energetics related to the cysteine nucleophilic attack on nitrile-carrying compounds. Activation energies were found to correlate well with experimental kinetic measures of reactivity with cysteine in phosphate buffer. The agreement between computations and experiments points to this DFT-based approach as a tool for predicting both nitrile reactivity toward cysteines and the toxicity of nitriles as electrophile agents.

Direct approaches to nitriles via highly efficient nitrogenation strategy through C-H or C-C bond cleavage

Because of the importance of nitrogen-containing compounds in chemistry and biology, organic chemists have long focused on the development of novel methodologies for their synthesis. For example, nitrogen-containing compounds show up within functional materials, as top-selling drugs, and as bioactive molecules. To synthesize these compounds in a green and sustainable way, researchers have focused on the direct functionalization of hydrocarbons via C-H or C-C bond cleavage. Although researchers have made significant progress in the direct functionalization of simple hydrocarbons, direct C-N bond formation via C-H or C-C bond cleavage remains challenging, in part because of the unstable character of some N-nucleophiles under oxidative conditions. The nitriles are versatile building blocks and precursors in organic synthesis. Recently, chemists have achieved the direct C-H cyanation with toxic cyanide salts in the presence of stoichiometric metal oxidants. In this Account, we describe recent progress made by our group in nitrile synthesis. C-H or C-C bond cleavage is a key process in our strategy, and azides or DMF serve as the nitrogen source. In these reactions, we successfully realized direct nitrile synthesis using a variety of hydrocarbon groups as nitrile precursors, including methyl, alkenyl, and alkynyl groups. We could carry out C(sp(3))-H functionalization on benzylic, allylic, and propargylic C-H bonds to produce diverse valuable synthetic nitriles. Mild oxidation of C═C double-bonds and C≡C triple-bonds also produced nitriles. The incorporation of nitrogen within the carbon skeleton typically involved the participation of azide reagents. Although some mechanistic details remain unclear, studies of these nitrogenation reactions implicate the involvement of a cation or radical intermediate, and an oxidative rearrangement of azide intermediate produced the nitrile. We also explored environmentally friendly oxidants, such as molecular oxygen, to make our synthetic strategy more attractive. Our direct nitrile synthesis methodologies have potential applications in the synthesis of biologically active molecules and drug candidates.

Palladium(ii)-catalyzed direct conversion of allyl arenes into alkenyl nitriles

Alkenyl nitriles can be easily accessed by Pd(ii)-catalyzed reaction of allyl arenes with tert-butyl nitrite as both the nitrogen source and oxidant and N-hydroxyphthalimide as the co-catalyst.

Palladium-catalyzed tandem reaction of 2-hydroxyarylacetonitriles with sodium sulfinates: one-pot synthesis of 2-arylbenzofurans

Palladium-catalyzed desulfinative addition and intramolecular annulation tandem reactions of 2-hydroxyarylacetonitriles with sodium sulfinates for one-pot synthesis of 2-arylbenzofurans.

Copper catalyzed nitrile synthesis from aryl halides using formamide as a nitrile source

A simple and efficient protocol has been developed for nitrile synthesis from aryl halides in the presence of an inexpensive and easily available copper catalyst along with triphenyl phosphine ligand.

Picomolar inhibitors of HIV reverse transcriptase featuring bicyclic replacement of a cyanovinylphenyl group

Members of the catechol diether class are highly potent non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTIs). The most active compounds yield EC50 values below 0.5 nM in assays using human T-cells infected by wild-type HIV-1. However, these compounds such as rilpivirine, the most recently FDA-approved NNRTI, bear a cyanovinylphenyl (CVP) group. This is an uncommon substructure in drugs that gives reactivity concerns. In the present work, computer simulations were used to design bicyclic replacements for the CVP group. The predicted viability of a 2-cyanoindolizinyl alternative was confirmed experimentally and provided compounds with 0.4 nM activity against the wild-type virus. The compounds also performed well with EC50 values of 10 nM against the challenging HIV-1 variant that contains the Lys103Asn/Tyr181Cys double mutation in the RT enzyme. Indolyl and benzofuranyl analogues were also investigated; the most potent compounds in these cases have EC50 values toward wild-type HIV-1 near 10 nM and high-nanomolar activities toward the double-variant. The structural expectations from the modeling were much enhanced by obtaining an X-ray crystal structure at 2.88 Å resolution for the complex of the parent 2-cyanoindolizine 10b and HIV-1 RT. The aqueous solubilities of the most potent indolizine analogues were also measured to be ~40 μg/mL, which is similar to that for the approved drug efavirenz and ~1000-fold greater than for rilpivirine.

Direct transformation of methyl imines to α-iminonitriles under mild and transition-metal-free conditions

A novel transformation of methyl imines into α-iminonitriles under mild and transition-metal-free conditions is described. Three C sp 3-H bonds are cleaved in a radical pathway at room temperature under air. Simple bromide salts are employed to assist this radical process (see scheme; FG=functional group, PIDA = iodobenzene diacetate, TMS = trimethylsilyl).

Copper-mediated transformation of organosilanes to nitriles with DMF and ammonium iodide

Cyanation of aryl-, diaryldimethyl-, and styrylsilanes was developed for the first time under copper-mediated oxidative conditions using ammonium iodide and DMF as the combined source of nitrogen and carbon atom of the introduced cyano unit, respectively. The reaction was observed to proceed in a two-step process: initial conversion of organosilanes to their iodo intermediates and then cyanation. This method has a broad substrate scope with high functional group tolerance.