Β-unsaturated Nitriles Research Articles

HFIP-driven Schmidt-type reaction enables chromone-3-carbonitriles and its applications.

Chromone-3-carbonitrile has been extensively studied in a panel of high-value transformations. However, existing protocols for the synthesis of this scaffold are often constrained by the structure of the starting materials and harsh conditions. To address these issues, we present a novel strategy that HFIP (hexafluoroisopropanol)-driven strategy, enables chromone-3-carbonitriles synthesis without undesirable side reactions. This protocol features readily available feedstocks, mild conditions, catalytic amount of acid and good to excellent yields. The utility of this chemistry is further demonstrated by amenable modifications of chromone-pyrimidines and imidazoles. Moreover, the analogous transformation of aldehydes is successfully constructed to achieve useful compounds such as 2-hydroxybenzonitriles, heterocyclic nitriles, and α, β-unsaturated nitriles. The HFIP-driven strategy offers an interesting access to different types of nitriles in a sustainably manner.

A Ru-Complex Tethered to a N-Rich Covalent Triazine Framework for Tandem Aerobic Oxidation-Knoevenagel Condensation Reactions.

Herein, a highly N-rich covalent triazine framework (CTF) is applied as support for a RuIII complex. The bipyridine sites within the CTF provide excellent anchoring points for the [Ru(acac)2(CH3CN)2]PF6 complex. The obtained robust RuIII@bipy-CTF material was applied for the selective tandem aerobic oxidation-Knoevenagel condensation reaction. The presented system shows a high catalytic performance (>80% conversion of alcohols to α, β-unsaturated nitriles) without the use of expensive noble metals. The bipy-CTF not only acts as the catalyst support but also provides the active sites for both aerobic oxidation and Knoevenagel condensation reactions. This work highlights a new perspective for the development of highly efficient and robust heterogeneous catalysts applying CTFs for cascade catalysis.

Interaction dust – plasma in Titan's ionosphere: An experimental simulation of aerosols erosion

Organic aerosols accumulated in Titan's orange haze start forming in its ionosphere. This upper part of the atmosphere is highly reactive and complex ion chemistry takes place at altitudes from 1200 to 900 km. The ionosphere is a nitrogen plasma with a few percent of methane and hydrogen. Carbon from methane enables the formation of macromolecules with long organic chains, finally leading to the organic aerosols. On the other hand, we suspect that hydrogen and the protonated ions have a different erosive effect on the aerosols.Here we experimentally studied the effect of hydrogen and protonated species on organic aerosols. Analogues of Titan's aerosols were formed in a radiofrequency capacitively coupled plasma (RF CCP) discharge in 95% N2 and 5% CH4. Thereafter, the aerosols were exposed to a DC plasma in 99% N2 and 1% H2. Samples were analysed by scanning electron microscopy and in situ infrared transmission spectroscopy. Two pellet techniques – KBr pressed pellets and thin metallic grids - were compared to confirm that modifications seen are not due to the material used to make the pellet.We observed that the spherical aerosols of ~500 nm in diameter were eroded under N2-H2 plasma exposure, with the formation of holes of ~10 nm at their surface. Aerosols were globally removed from the pellet by the plasma. IR spectra showed a faster disappearance of isonitriles and/or carbo-diimides compared to the global band of nitriles. The opposite effect was seen with β-unsaturated nitriles and/or cyanamides. Double bonds as CC and CN were more affected than amines and CH bonds. NH and CH absorption bands kept a similar ratio in intensity and their shape did not vary.Therefore, it seems that carbon and hydrogen play opposite roles in Titan's ionosphere: the carbon from methane leads to organic growth while hydrogen and protonated species erode the aerosols and react preferentially with unsaturated chemical functions.

Prolinamide functionalized polyacrylonitrile fiber with tunable linker length and surface microenvironment as efficient catalyst for Knoevenagel condensation and related multicomponent tandem reactions

A series of new prolinamide polyacrylonitrile fiber catalysts with tunable length of alkyl linker and different linker group were prepared by covalent bonding for the first time and well characterized by mechanical strength, FT-IR, XRD, EA, TGA, SEM and water contact angel. The catalytic activities of these fiber catalysts were evaluated in Knoevenagel condensation and one-pot Knoevenagel-Michael multicomponent tandem reactions to synthesize α, β-unsaturated nitrile and 2-amino-4H-chromene derivatives in water. The result show that the suitable linker length attaching amines to fiber matrix as well as the constructed hydrophobic microenvironment by linker group within the surface layers of fiber materials effectively promotes the reactions. In addition, the good swollen capacity of fiber in solvent ensure that the reaction proceed well. Fiber catalyst PANPA−2F modified by prolinamide with a C2 alkyl chain exhibited the best catalytic performance and can be easily recovered and reused for at least ten consecutive cycles without significant loss of catalytic activity and active sites leaching.

Synthesis of the allelochemical alliarinoside present in garlic mustard (Alliaria petiolata), an invasive plant species in North America

The allelochemical alliarinoside present in garlic mustard (Alliaria petiolata), an invasive plant species in North America, was chemically synthesized using an efficient and practical synthetic strategy based on a simple reaction sequence. Commercially available 1,2,3,4,6-penta-O-acetyl-β-d-glucopyranose was converted into prop-2-enyl 2′,3′,4′,6′-tetra-O-acetyl-β-d-glucopyranoside and subjected to epoxidation. In a one-pot reaction, ring-opening of the epoxide using TMSCN under solvent free conditions followed by treatment of the formed trimethylsilyloxy nitrile with pyridine and phosphoryl chloride, afforded the acetylated β-unsaturated nitriles (Z)-4-(2′,3′,4′,6′-tetra-O-β-d-glucopyranosyloxy)but-2-enenitrile and its isomer (E)-4-(2′,3′,4′,6′-tetra-O-β-d-glucopyranosyloxy)but-2-enenitrile. Deacetylation of Z- and/or E-isomers afforded the target molecules alliarinoside and its isomer.

One-pot tandem catalytic synthesis of α, β-unsaturated nitriles from alcohol with nitriles in aqueous phase

Pd1–Au1 bimetal catalysts supported on basic layered double hydroxide (LDH) have been prepared conveniently with surface impregnation methods and structurally characterized by XRD, TEM and XPS. The nanoparticles were highly dispersed on LDH with an average size of 2.08±0.3nm and showed a strong cooperative effect between Au and Pd for the step of the alcohol oxidation. Moreover, the present hydrotalcite-supported bimetal catalysts can catalyze efficiently one-pot α-arylation reactions of nitriles with various alcohols in aqueous phase through tandem reactions. The bimetal catalyst has been extended for a broad substrate scope and recycled for at least 4 times.

KF/Al2O3/PEG-400: An Efficient Catalytic System for the Fiesselmann-Type Synthesis of Thiophene Derivatives

A simple and mild protocol has been developed for the synthesis of novel steroidal and nonsteroidal thiophene derivatives from β-halo-α,β-unsaturated aldehydes using KF/Al₂O₃/PEG-400 as an efficient catalytic system. The β-halo-α,β-unsaturated aldehydes are synthesized from the corresponding ketones using Vilsmeier­ formylation reaction and converted into β-halo-α,β-unsaturated nitriles. The synthetic protocol is subsequently applied to the synthesis of 3-aminothiophene derivatives using β-halo-α,β-unsaturated nitriles.

Highly Z-selective synthesis of α,β-unsaturated nitriles using the Horner–Wadsworth–Emmons reaction

A new HWE reagent, (o-tBuC6H4O)2P(O)CH2CN (2e), reacts with various types of aldehydes to give Z-α,β-unsaturated nitriles with 86% to >99% Z-selectivity. Especially, the reaction of 2e with bulkier aldehydes, both aromatic and aliphatic, gave the Z-olefins with extremely high selectivity. The combination of t-BuOK and 18-crown-6 (1equiv) is the base of choice for aromatic aldehydes and t-BuOK is generally the base of choice for aliphatic aldehydes.

Synthesis and applications of quaternized highly branched polyacrylamide as a novel multi-site polymeric phase transfer catalyst

In current study, quaternized highly branched polyacrylamide (HBAA) was synthesized and used as an efficient multi-site polymeric phase transfer catalyst in nucleophilic substitution reactions and also in synthesis of α, β-unsaturated nitriles from reaction of acetonitrile and carbonyl compounds. The quaternized HBAA was synthesized via two steps. First, HBAA was synthesized via self-condensing vinyl polymerization of acrylamide at appropriate molar ratio of monomer to diperiodatocuprate(III). In the second step, 3-acrylamidopropyl trimethylammonium iodide was polymerized on peripheral area of the HBAA in the presence of diperiodatocuprate(III) solution again. The thermal behavior of HBAA and that of the quaternized HBAA were studied by DSC and TGA analysis. This phase transfer catalyst was easily recovered after reaction and reused several times without any loss of activity.

Gallium (iii)-catalysed bromocyanation of alkynes: regio- and stereoselective synthesis of β-bromo-α,β-unsaturated nitriles

Treatment of arylacetylenes and cyanogen bromide in ClCH(2)CH(2)Cl with a catalytic amount of GaCl(3) afforded (Z)-β-bromoacrylonitriles with high regio- and stereoselectivity.

ChemInform Abstract: A Novel Synthesis of β-Perfluoroalkylated α,β- Unsaturated Nitriles.

A novel intramolecular Wittig reaction proceeding via ylide-anion formation and protonation and its application to the synthesis of β-perfluoroalkyl-α,β-unsaturated nitriles is described.

ChemInform Abstract: Solid Base-Catalyzed Reaction of Nitriles with Methanol to Form α ,β-Unsaturated Nitriles. Part 2. Surface Base Property and Reaction Mechanism

ChemInform Abstract: Solid Base-Catalyzed Reaction of Nitriles with Methanol to Form α ,β-Unsaturated Nitriles. Part 2. Surface Base Property and Reaction Mechanism

ChemInform Abstract: A Convenient One-Pot Synthesis of α-Fluoro-α,β- unsaturated Nitriles from Diethyl Cyanofluoromethanephosphonate.

The carbanion of diethyl 1-cyano-1-fluoromethanephosphonate 3, generated in situ from diethyl cyanomethanephosphonate 2 and N-fluorobis(trifluoromethanesulfonyl)imide 1, undergoes the Wittig–Horner reaction with aldehydes and ketones to yield α-fluoro-α,β-unsaturated nitriles 5.

The Baylis–Hillman Adducts as Valuable Source for One‐Pot Multi‐Step Synthesis: A Facile Synthesis of Substituted Piperidin‐2‐ones

AbstractA facile, convenient, and one‐pot multi‐step synthesis of substituted piperidin‐2‐ones from the Baylis–Hillman alcohols derived from various aldehydes and acrylonitrile, involving Johnson–Claisen rearrangement, reduction of an α,β‐unsaturated nitrile moiety into the saturated amine‐skeleton, followed by cyclization, in an operationally simple procedure, is described.

Formal Synthesis of (+)-Indatraline

The key step in this formal synthesis of (+)-indatraline is a catalytic asymmetric conjugate reduction (B → C) of a β,β-diaryl-α,β-unsaturated nitrile using a copper hydride coordinated to (R)-Josiphos. A further eleven examples are ­reported (78-91% yield) with typical ee values ­exceeding 90% even in cases where the two aryl groups have a similar steric demand.

Exploring the versatility of the Johnson–Claisen rearrangement: access to functionally versatile δ-ethoxycarbonyl-α,β-unsaturated nitriles

A practical entry into δ-ethoxycarbonyl-α,β-unsaturated nitriles is described. α,β-Unsaturated aldehydes were converted to cyanohydrins, by employing either KCN in aqueous acid, or by using TMSCN with catalytic K 2CO 3, followed by acid hydrolysis of the TMS ether. These cyanohydrins underwent a Claisen rearrangement employing a modified Johnson–Claisen protocol to yield unsaturated nitriles in good yields and with moderate E/ Z selectivity.

Optical properties of modified grafted polypropylene

The optical properties of PP thin films of radiation-graft copolymerization of N-vinyl-2-pyrrlidone and the modification of grafted polymer by α, β-unsaturated nitrile are investigated in the UV–visible region. The absorption coefficient (α) is calculated as a function of the degree of grafting and modification copolymerization. The values of the optical band gap (Eg) have been obtained from the indirect allowed transitions in k-space. The width of the tails of localized states in the band gap (Eu) was evaluated from Urbach edges. Both the parameters (Eg) and (Eu) vary with the degree of grafting and the modification of grafting copolymers for irradiated and unirradiated samples.

Sequential Knoevenagel Reaction/Mislow-Evans Rearrangement Catalyzed by Heterogeneous Amine Grafted on Silica in Water, Leading to γ-Hydroxy-α,β-unsaturated Nitrile

y-Hydroxy-α,β-unsaturated nitrile was obtained by the reaction of a-arylsulfinylacetonitrile with aldehyde in water, which was catalyzed by N,N-diethylaminopropylated silica gel. The overall transformation proceeded via five sequential reactions, 1,2-addition of acetonitrile, dehydration (Knoevenagel condensation), isomerization of the double bond, rearrangement of sulfinyl group (Mislow-Evans rearrangement) and hydrolysis of sulfinyl ester. The reaction condition was mild such that the AcO, TBMDSO or OTHP group remained intact in the products.

Synthesis of E-vinylogous ( R)-amino acid derivatives via metal-catalyzed allylic substitutions on enzyme-derived substrates

Oxynitrilase-derived allylic ( R)-cyanohydrin carbonates 3 and allylic ( R)-α-hydroxy ester carbonates 6 were examined as substrates for a palladium(0)-catalyzed allylic azidation reaction. The enantioselectivities and cis/trans diastereoselectivities of the concomitant 1,3-chirality transposition step were studied. The cyano carbonates 3a– c were found to be unimpressive substrates producing γ-azido-α,β-unsaturated nitriles 4a– c with cis/trans ratios that approached unity and gave enantiomeric excesses that ranged from 57% to 85%. In contrast, ester carbonates 6a and b were excellent substrates for the reaction exclusively affording trans substitution products 7a and b in identical enantiomeric excesses of 95% ee.

A convenient synthesis of (E)- α-halo-α,β-unsaturated nitriles

E)-α-Halo-α, β-unsaturated nitriles were synthesized through the tandem nucleophilic substitution-Wittig reaction of α-cyano-α-hypervalent iodine phosphonium ylide that was used as umpolung ylide.