CuFe2O4 nanoparticles: a magnetically recoverable and reusable catalyst for the synthesis of 5-substituted 1H-tetrazoles

An efficient and economical protocol for the synthesis of 5-substituted 1H-tetrazoles from various nitriles and sodium azide is described using magnetically recoverable and reusable CuFe₂O₄ nanoparticles. A wide variety of aryl nitriles underwent [2+3] cycloaddition under mild reaction conditions to afford tetrazoles in good to excellent yields. The catalyst was magnetically separated and reused five times without significant loss of catalytic activity.     

Efficient synthesis of fluorinated α- and β-amino nitriles from fluoroalkylated α,β-unsaturated imines

A simple and efficient synthesis of fluoroalkylated α-amino nitrile (4) derivatives by regioselective 1,2-addition of trimethylsilyl cyanide to fluoroalkylated α,β-unsaturated imines (1) is described. Fluoroalkylated β-amino nitriles (7) are also prepared by regioselective 1,2-addition of α-carbanions derived from acetonitrile to fluoroalkylated α,β-unsaturated imines (1). Fluoroalkylated α-(4) and β-amino nitriles (7) are also prepared through an ‘one pot’ procedure by reaction of enaminophosphonate 2 with BuLi, addition of aldehydes and subsequent addition of either trimethylsilyl cyanide or α-carbanion derived from acetonitrile. Basic hydrolysis of α-(4) and β-amino nitriles (7) gives fluoroalkylated α-(5) and β-amino acids (8).     

One-pot selective syntheses of 5-azaindoles through zirconocene-mediated multicomponent reactions with three different nitrile components and one alkyne component

5-Azaindoles either with three different substituents at their 2-, 4-, and 6-positions or with two identical substituents at their 2- and 6-positions and a different one at the 4-position, were obtained in good to excellent isolated yields by a zirconocene-mediated multicomponent process. Each reaction involved four organic partners, comprising a Si-tethered diyne, one tBuCN component, and two (either different or identical) nitriles. All these four components were combined through the action of a Cp(2)Zr(II) species into a three-ring fused Zr/Si-containing organometallic complex in a perfectly chemo- and regioselective manner. This multicomponent reaction process consisted of three reaction steps, all of which were made clear through the isolation and characterization of their corresponding organometallic intermediates: the zirconacyclopropene-azasilacyclopentadienes 2, the allenyl-aza-zirconacycles 3, and the three-ring fused complexes 6. X-ray single-crystal structural analyses of two three-ring fused Zr/Si-containing intermediates and two 5-azaindoles unambiguously showed the positions of the different substituents and the regioselectivity. Iminopyrrole derivatives could be also highly selectively prepared from a Si-tethered diyne and two different nitriles.     

Nickel-catalyzed, cascade cycloadditions of 1-ethynyl-8-halonaphthalenes with nitriles: synthesis, structure, and physical properties of new pyrroloarenes

The reaction of 1-ethynyl-8-halonaphthalenes 1 with nitriles in the presence of the catalytic system [NiBr(2)(dppe)]/Zn (dppe=1,2-bis(diphenylphosphino)ethane) is found to produce unusual pyrroloarenes 2. The carbon-nitrogen triple bond in nitrile is activated twice, and five new bonds are formed in a one-pot transformation, which causes a pyrrole and two six-membered rings to be generated simultaneously. The scope and limitations of this reaction are examined. Similarly, alkyl-bridged diynes also furnish the corresponding polycycles. Diaryl-substituted cycloadducts 2 (R(1)=Ar) are fluxional, because of the restriction in rotation of the aryl groups. The rotational barrier is studied by performing (1)H NMR experiments at various temperatures. The structures of several compounds are determined by X-ray crystallographic analysis. The photophysical and electrochemical properties of the pyrroloarenes are also investigated.     

Diastereoselective addition of trimethylsilyl cyanide to chiral O‐, S‐ and N‐heterocyclic aldimines

Systematic investigation of asymmetric trimethylsilylcyanation of heterocyclic azomethines has been realized. The addition of trimethylsilyl cyanide to optically active furan, thiophene and pyridine aldimines, derived from (R)‐ and (S)‐1‐phenylethylamine, was studied in the presence of Lewis acids, and a series of the corresponding α‐amino nitriles was obtained in fair to good yields (up to 91%). Unsaturated nitriles were also formed from pyridine imines. The sense of asymmetric induction and the degree of diastereoselectivity in the synthesis of α‐amino nitriles were determined by means of ¹H NMR. The stereochemical outcome is a result of the same sense of asymmetric induction: Re face attack to the (S)‐imines and Si face addition to the (R)‐imines took place. The (R,R)‐ (up to 81%) or (S,S)‐ (up to 87%) α‐amino nitriles predominated in the products obtained from the all furan, thiophene and pyridine (R)‐ or (S)‐imines respectively. Copyright © 2002 John Wiley & Sons, Ltd.     

Calcite and fluorite as catalyst for the Knövenagel condensation of malononitrile and methyl cyanoacetate under solvent-free conditions

When milled together with calcite or fluorite, malononitrile and methyl cyanoacetate readily underwent Knövenagel condensation with aromatic aldehydes, giving the corresponding arylidenemalononitriles and (E)-α-cyanocinnamic esters in good to excellent yield.     

Cotrimerization of mono- and dinitriles of perfluorocarboxylic acids under high pressures

Cotrimerization of mono- and dinitriles of perfluorocarboxylic acids under high pressures affords oligoperfluoroalkylenetriazines. These oligomers are highly efficient stabilizers of thermooxidative destruction of perfluoropolyethers, when they are contacting with metals at elevated temperatures.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1814–1816, September, 1995.