16610-80-3

The addition of hydrogen cyanide to both terminal and disubstituted acetylenes occurs with cis-stereospecificity in moderate to excellent yields when catalysed by a nickel(0) complex.

Cyanodiarylethene chromophores are able to undergo constitutional exchange via dynamic covalent chemistry (DCC). During this process, the central ethylene bridge of the molecular scaffold can be broken and thereby enables the assembly of a new combination of aryl moieties around the reformed ethylene bridge. The reversible CC double bond exchange has exemplarily been investigated using α-cyanostilbenes. Establishing a dynamic equilibrium reaction from α-cyanodiarylethene with arylacetonitriles under mild conditions has been the basis to access constitutional libraries of new photoswitches with potentially improved properties. When subject to irradiation with light of adequate wavelength, α-cyanodiarylethenes undergo Z/E isomerization followed by ring-closure. By screening the thus accessible dynamic chromophore libraries using a desired detection wavelength, we could identify specific dithienyl analogues that exhibit three-state photochromism. The combination of dynamic constitutional libraries of functional chromophores in combination with the light-guided screening and selection should lead to more rapid exploration of structural diversity dye chemistry.

We report nickel-catalyzed cyanation and hydrocyanation methods to prepare aryl nitriles and vinyl nitriles from aryl halides and alkynes, respectively. Using inexpensive and nontoxic 4-cyanopyridine N-oxide as the cyano shuttle, the methods provide an efficient approach to prepare aryl cyanides and vinyl nitriles under mild and operationally simple reaction conditions with a broad range of functional group tolerances. In hydrocyanation of alkynes, the method demonstrated good regioselectivity, producing predominantly E- or Z-alkenyl nitriles in a controlled manner and exclusively Markovnikov vinyl nitriles when internal diaryl alkynes and terminal alkynes were applied as the substrates, respectively. The preliminary mechanistic investigation indicated that the C-CN bond cleavage process is promoted by oxidative addition to the nickel(I) complex in the cyanation of aryl halides, and further studies via a series of deuterium exchange experiments indicated that water serves as the hydrogen source for the hydrocyanation of alkynes.

Ni-catalyzed decarbonylative cyanation of acyl chlorides with trimethylsilyl cyanide has been achieved. This transformation is applicable to the synthesis of an array of nitrile compounds bearing a wide range of functional groups under neutral conditions. The step-by-step experimental studies revealed that the reaction sequences of the present catalytic reaction are oxidative addition, transmetalation, decarbonylation, and reductive elimination.

The in situ generation of a "cyano" unit from readily available organic precursors is of high interest in synthetic chemistry. Herein, we report the first example of Ni-mediated dehydration of formamide to form "CN" and its subsequent catalytic applications in the hydrocyanation of alkynes and cyanation of aryl halides. Formamide can serve as a convenient source for the nitrile unit, in that it releases water as the only byproduct.

An efficient nickel-catalyzed cyanation of aryl sulfonates, fluorosulfonates, and sulfamates with Zn(CN)2 was developed, which provides a facile access to the nitrile products in generally good to excellent yields. The reaction is accomplished by using NiII complex as the precatalyst and DMAP as the additive. The method also displays wide functional group compatibility; for example, keto, methoxy, N,N-dimethylamino, cyano, ester, and pyridyl groups are well-tolerated during the reaction process.

A metal-free and direct alkene C?H cyanation is described. Directing groups are not required and the mechanism involves electrophilic activation of the alkene by a cyano iodine(III) species generated in situ from a [bis(trifluoroacetoxy)iodo]arene and tri

The first efficient and general nickel-catalyzed hydrocyanation of terminal alkynes with Zn(CN)2 in the presence of water has been developed. The reaction provides a regioselective protocol for the synthesis of functionalized vinyl nitriles with a range of structural diversity under mild reaction conditions while obviating use of the volatile and hazardous reagent of HCN. Deuterium-labeling experiments confirmed the role of water as the hydrogen source in this hydrocyanation reaction.

A fast condensation of indene with a wide range of aldehydes catalyzed by cesium hydroxide monohydrate (CsOH·H2O) for the synthesis of benzofulvenes with good to excellent yields was demonstrated. The condensation can be completed within a few minutes under room temperature and air atmosphere without the use of special ligands or phase-transfer catalysts. In addition, the ratio of indene to aldehydes played an important role in this reaction. The single condensation products 3 can be obtained as main products with a ratio of 1.2:1, whereas the double condensation products 4 can be obtained by changing the ratio to 1:2.2. This protocol provides an efficient, simple and general method for the synthesis of benzofulvenes 3 and double condensation products 4, which are important intermediates in the synthesis of numerous drugs and natural products.

Photoluminescence data are reported for two W(CO)4L complexes (L = 2-(1H-imidazol-2-yl)pyridine and 2-(2′-pyridyl)benzimidazole) in room-temperature solutions. The bidentate ligands consist of a pyridine and an imidazole moiety connected by a C-C bond. The complexes have been found to exhibit enhanced phosphorescence from the metal-to-ligand charge transfer (MLCT) excited state with quantum yields in the order of 10-3, almost two orders of magnitude higher than those reported for W(CO)4(diimine) complexes. One of the complexes W(CO)4(2-(2′-pyridyl)benzimidazole) can serve as an efficient visible-light photosensitiser for the isomerisation of aromatic alkenes with efficiency comparable to and even exceeding that of the well-studied ruthenium tris-bipyridine complex, Ru(bpy)Cl2.

A catalytic system for cyanation of aryl and vinyl halides with K4Fe(CN)6 based on a structurally tunable and nontoxic polymer backbone of polyamic type with biquinolyl fragments in the polymer chain capable of coordination to PdII ions is developed. The catalyst is eligible for thermal and microwave activation; in the latter case the reaction time is dramatically decreased. Cyanation of vinyl bromides occurs stereoselectively, and the configuration of the starting alkene is retained; even for Z-isomers the impact of configuration inversion is less than 5%. The polymer-based Pd catalyst is applicable for one-pot multi-step synthesis of the precursors of mesogenic structures of biphenyl type. Consecutive cross-coupling and cyanation reactions can be performed in the presence of the same portion of catalyst, in the same solvent, without isolation of intermediate products.

The direct synthesis of nitriles from commercially available or easily prepared aldehydes has been achieved. O-(4-CF3-benzoyl)-hydroxylamine (CF3-BHA) was utilized as the nitrogen source to generate O-acyl oximes in situ with aldehydes, which can be converted to a nitrile with the assistance of a Bronsted acid. Several aliphatic, aromatic, and α,β-unsaturated nitriles that contain different functional groups were prepared in high yields (up to 94% yield). This method has notable advantages, such as simple and mild conditions, high yields, and good functional group tolerance.

Amine functionalized silica coated Fe3O4 nanoparticles (SiO2@MNP-A) were successfully prepared as a novel heterogeneous amine. The catalyst was characterized by XRD, FT-IR, TEM, magnetic measurement, elemental analysis and was found to be a magnetically separable and highly active catalyst for ambient Knoevenagel condensation of aromatic aldehydes and a-aromatic (heteroaromatic or polyaromatic)-substituted methylene compounds in water under ultrasonic irradiation to afford the corresponding products in good to excellent yields. Very interestingly, SiO2@MNP-A successfully catalyze the reaction of the non-cyano substituted compound with benzaldehyde to achieve a key intermediate for the preparation of Atorvastatin calcium in green and atom-economic manner. In addition, the catalyst SiO2@MNP-A can be reused for 8 times without any obvious loss of its activity. The role of ultrasonication in the Knoevenagel condensation was also discussed with the assistance of UV-vis spectrometry.

An efficient, green and practical approach to synthesize alkenyl nitriles using new supported Cu(II) catalyst via aromatic aldehydes and acetonitrile was developed. The novel catalyst was characterized by FT-IR, XRD, SEM/EDX, TEM, TGA and VSM. Interestingly, the catalyst was found to be active for synthesis of alkenyl nitriles, which were readily obtained in good yields under mild conditions. But most importantly, the original catalyst could be conveniently recovered and recycled from the reaction system by applying an external magnet and reused in four cycles without significant loss in catalytic activity. Graphical Abstract: [Figure not available: see fulltext.]

(Figure presented) A novel approach to aryl or alkenyl nitriles from benzyl and allyl halides has been developed. A tandem TBAB-catalyzed substitution and the subsequent novel oxidative rearrangement are involved in this transformation. To the best of our knowledge, this is the first transformation from allyl halides to alkenyl nitriles. The broad reaction scope and the mild conditions may make these methods of use in organic synthesis.

Experimental evidence is assessed concerning the nature of organonickel intermediates involved in the cyclotrimerization and the cyclotetramerization of alkynes, as well as the cross-oligomerization of alkynes with carbene sources, as mediated by nickel(0) complexes. In the former processes a sequential series of nickelacycloalkapolyenes are the productive intermediates and in the latter cross-oligomerizations nickel(0)-carbene complexes themselves are critical precursors to the ultimately generated carbocycles.

Bromodestannylation reactions are reported for several functional substituted organotin compounds in carbon tetrachloride and acetonitrile as solvents.The reactions in carbon tetrachloride proceed with a high degree of retention of configuration at the carbon involved in the electrophilic substitution, while in a polar solvent there is an increase in the amount of inversion product formed.The electrophilic cleavage in the β-trialkylstannyl esters takes place with a complete reversal of the normal sequence of Sn-C bond cleavage by halogens; this is explained by tin assistance.The configuration of some 3-trialkylstannylpropanenitriles, β-bromonitriles and β-bromoesters are assigned.Full, 1H, 13C and 119Sn NMR data are given.

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The condensation of a series of CH acids (fluorene, phenylacetonitrile, ethene) with aromatic aldehydes was realized in the aqueous sodium hydroxide-organic solvent-phase-transfer catayst system. 9-Substituted fluorenes do not enter into condensation under the indicated conditions.The condensation of fluorene, PhCH2CN, CH2(CN)2, and CH2(CN)COOEt with benzaldehyde and also of CH2(CN)COOEt with cyclohexanone was realized in the presence of tetrabutylammonium fluoride , deposited on silika gel.It was shown that the yield of the produt from crotonic condensation in the reaction of CH2(COOEt)2 with benzaldehyde is small, and this is due to the instability of PhCH=C(COOEt)2 under the reaction conditions.Sodiomalonic ester was condensed with benzaldehyde in the presence of titanium tetrachloride or aluminum chloride.

The CdS powder photomediated cis-trans isomerization of six styrene derivatives has been demonstrated.The reaction with cis-stilbene is quenched by electron donors (methoxybenzenes and pyrene) and is affected by the amount of CdS used, light intensity, and the temperature.A minimal simple scheme involving the radical cation is proposed, as a basis for further work, to which Langmuir-Hinshelwood and Freundlich kinetic treatments are applied, the latter somewhat more successfully.The presence of oxygen inhibits the reaction.

Under nickel(0) mediation, trimethylsilyl(iso)cyanide serves as both a useful synhydrocyanating agent and a carbonylating agent for alkynes.

Hydrogen cyanide will add to alkynes bearing a wide range of substituents with cis stereospecificity, high regioselectivity, and in moderate-to-good yields, when the reaction is catalysed by tetrakis-(triphenyl phosphite)nickel(0).

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