New catalytic effect of thiourea on the oxidative cyanation of N-aryltetrahydroisoquinolines

Thiourea itself has been introduced as a mild and efficient organocatalyst for the oxidative α -cyanation of N-aryltetrahydroisoquinolines (THIQs) with trimethylsilyl cyanide (TMSCN), giving the corresponding products in good to excellent yields. Experimental investigations demonstrated that thiourea acts as a radical initiator by abstracting hydroxyl radical (OH) from tert-butyl hydroperoxide (TBHP) directly instead of non-covalent hydrogen bondings (H-bondings) activation. The use of thiourea as a radical initiator offers a new avenue for innovative chemical transformations in organocatalyzed radical chemistry.     

Improving palladium-catalyzed cyanation of aryl halides: development of a state-of-the-art methodology using potassium hexacyanoferrate(II) as cyanating agent

Benzonitriles are easily accessible via palladium-catalyzed cyanation of aryl halides using potassium hexacyanoferrate(II) as cyanide source. This method is applicable on both activated and deactivated aryl and heteroaryl bromides and activated chlorides giving the corresponding benzonitriles in good to excellent yield. Advantageously, the used cyanating agent is non-toxic and cheap. The presented catalyst system is rather simple and it is not necessary to add expensive phosphines, making the novel method also attractive for industrial applications.     

Statistical experimental design-driven discovery of room-temperature conditions for palladium-catalyzed cyanation of aryl bromides

A combination of Pd₂(dba)₃·CHCl₃ (0.5 mol %) and commercially available, air-stable phosphonium salt [(t-Bu)₃PH]BF₄ (1.4 mol %) in a presence of Zn powder and Zn(CN)₂ as the cyanide source comprises an extremely efficient catalyst system for the cyanation of a diverse array of aryl bromides, at room temperature. This result emerged from an experimental strategy that combines the advantages of parallel, automated experimentation with the design of experiments (DOE) for the effective definition of an optimal set of reaction conditions.     

Recent advances in the boration and cyanation functionalization of alkenes and alkynes

Alkenyl boron-esters and acrylonitrile groups are key structural functional groups found in dyes, pesticides, fluorescent compounds, functional materials, and biologically active drugs. Considerable efforts have been devoted for the introduction of boron-esters and acrylonitrile groups by using alkenes and alkynes conversion routes for boronation, hydroboronation, dehydrogenative boronation, cyanation, hydrocyanation, alkylcyanation, cyanomethylation. These reported methodologies are very valuable for the industrial production of acrylonitriles and alkenyl boron esters.     

Palladium supported on zinc ferrite: an efficient catalyst for ligand free C–C and C–O cross coupling reactions

An efficient superparamagnetic Pd–ZnFe₂O₄ solid catalyst has been synthesized by loading Pd(0) species on zinc ferrite nanoparticles. Sonogashira cross couplings between terminal alkynes and aryl halides were achieved in the absence of any Cu co-catalyst. A Heck–Matsuda coupling reaction of structurally different aryldiazonium tetrafluoroborate substrates was preceded at 40 °C in water. Cyanation of aryl halides was successfully done using K₄[Fe(CN)₆] as the cyanide source over Pd–ZnFe₂O₄. The catalyst was also employed for Ullmann type cross coupling reactions. Excellent yield of the products, reusability, and uncomplicated work-up make this catalyst efficient for C–C and C–O coupling reactions. Good yield of products, easy separation, and negligible leaching of Pd from the catalyst surface confirm the true heterogeneity in these catalytic reactions.     

硅胶功能化的N-丙哌嗪固载钯纳米粒子作为有效的多相催化剂用于氰化反应(英文)

An efficient heterogeneous Pd catalytic system has been developed, based on immobilization of Pd nanoparticles (PNPs) on a silica-bonded N-propylpiperazine (SBNPP) substrate. The SBNPP substrate effectively stabilizes the PNPs and improves their stability against aggregation. The catalytic activity of this catalyst was investigated in the cyanation of aryl halides with K4[Fe(CN)6 ] as the cyanide source. The catalyst could be recycled several times without appreciable loss of catalytic activity.     

Sulfate additives generate robust and highly active palladium catalysts for the cyanation of aryl chlorides

The use of sulfate additives such as H₂SO₄ greatly increases the reactivity of palladium catalysts for the cyanation of aryl and heteroaryl chlorides and renders them more robust toward adventitious air. Using this method, a wide variety of aromatic and heteroaromatic nitriles were prepared in high yield.     

An efficient palladium catalytic system for microwave assisted cyanation of aryl halides

Application of a new catalytic system for cyanation reaction of various aryl halides using K₄[Fe(CN)₆] as cyanating source was examined. The reactions were performed under microwave irradiation and results showed that application of this catalytic system and DMF at 130 °C minimized the reaction times from hours to minutes in good to excellent yields.     

Synthesis of butyrolactones by nickel-catalyzed reductive cyanation of alkynols in water

One-pot catalytic synthesis of butyrolactones from alkynols under mild conditions is described here. The methodology involves the use of the K₂[Ni(CN)₄]/NaBH₄ system in presence of KCN and water. According to the experimental evidences, a possible mechanism pathway is suggested, which involves the nickel-catalyzed reductive cyanation of alkynol, followed by nitrile hydration, reduction of double bond and lactonization.     

Tricyanated Ferrocenes; Isolation,structure, electrochemistry and DFT calculations

1,2,3- Tricyanoferrocene and 1,3-dibromo-2,4,5-tricyanoferrocene have been synthesized via metallation and usage of dimethylmalononitrile (DMMN) as cyanating agent. They are the first compounds where three nitrile functions could be introduced into the ferrocene sceleton. Further studies on the electrophilic cyanation of lithiated haloferrocenes [Fe(C₅H_mX_4-mLi)(C₅H₅)] (X=Cl, Br; m=0–3) show the formation of complex mixtures of cyano-halo-ferrocenes [Fe{C₅H_mX_5-m-n(CN)_n}(C₅H₅)] (m=0–3, n=0–3) most likely induced by “halogen-dance” reactions. The molecular and crystal structures of [Fe{C₅H₂(CN)₃}(C₅H₅)] and [Fe(C₅Cl₄CN)(C₅H₅)] are discussed. Cyclic voltametric studies of both tricyanoferrocenes show irreversible oxidations at very high potentials (E_onset≈845 mV and 945 mV, respectively, vs FcH/FcH⁺).