Studies on thermal degradation of benzylidene malononitriles

Thermal decomposition studies have been carried out using flash vacuum thermolysis (FVT) to find out the decomposition temperature for benzylidene malononitriles (BMNs) including 2-chlorobenzylidene malononitrile (cs), a widely used riot control agent. The FVT studies have been carried out in a specially designed all glass assembly at various temperatures ranging from 300 to 600°C. A number of rearranged products along with hydrogen cyanide were obtained as major decomposition products. The products were analysed and the structures were confirmed by GC/MS. the thermal behaviour of BMNs has also been investigated by TG under nitrogen atmosphere. These studies show that the pyrotechnic mixture for tear gas munitions should not have burst temperature above 300°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Normal coordinate analysis of malononitriles: IV. Dialkylmalononitriles

The infrared and Raman spectra of some dialkylmalononitriles have been recorded. The assignments of the fundamentals are proposed and a normal coordinate analysis carried out using the Becher and Mattes method for the dimethyl derivative. Attention was given to the frequency and the Raman intensity of the v(CN) band.     

Organocatalytic enantioselective conjugate addition of ketones to isatylidine malononitriles

An enantioselective Michael addition of ketones to alkylidenemalononitriles catalyzed by chiral primary amine I with (R)-5c as a co-catalyst in good yields (>90%) and with good enantioselectivities (85-96% ee) has been developed. The strategy has also been extended to a three-component version through a domino Knoevenagel/Michael sequence with similar or better outcomes.     

Conjugate allylation reactions of alkylidene malononitriles mediated by NHC-ligated palladium catalysts

Conjugate allylation of malononitriles is reported using catalytic N-heterocyclic carbene-ligated palladium complexes. This conjugate allylation reaction yields a variety of monoallylated products. These results contrast the bis-allylation of malononitriles using other palladium-based catalysts. This reaction tolerates a wide variety of functional groups including aryl groups, heteroaromatics, and aliphatic substituents to provide the desired products in good to excellent yields. Derivativation of the monoallylation products to form a triamino pyrimidine is demonstrated.     

R'Hg- and Ph3PAu-Derivatives of substituted malononitriles RCH(CN)2

The organomercurials RC(HgR')(CN)₂ (R = Me, Ph; R¹ = Ph, CH₂Ph) have been obtained by the action of organomercury hydroxides R'HgOH or acetates R'HgOAc on substituted malonodinitriles RCH(CN)₂- (Ph₃PAu₃O+BF₄ reacts with the same nitriles to give organogold derivatives RC(AuPPh₃)(CN)₂. The study of the structures of organomercury and -gold compounds by¹H,³¹P and¹⁹⁹Hg NMR spectra as well as by IR spectra show that these compounds exist mainly in the C-form. The degenerated exchange reaction involving the cleavage of C-Hg bond takes place in the phenylmercury derivative of methylmalonodinitrile. Organomercury derivatives of substituted malonodinitriles are stable with respect to symmetrization in solution, in contrast to PhCH(HgPh)CN studied previously.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 129–133, January, 1994.     

NMR Analysis of Substituent Effect of Arymethylene‐malononitriles and Malonates

A series of arylmethylene‐malononitriles and malonates were prepared from the condensation of arylaldehydes and malononitriles and malonates, respectively. The function of substituents on the carbon‐13 chemical shifts of the Cα and Cβ was studied. The correlation between Hammett's constants and the substituent chemical shifts demonstrates a negative slope for Cα and positive for C_β (1, C_α:ρ = ‐3.877, r² = 0.979; C_β:ρ = 6.899, r² = 0.984; 2, C_α:ρ = ‐2.817, r² = 0.926; C_β:ρ = 5.355, r² = 0.950). The large slopes for C_β for both series compounds resemble our previous studies on the arylcyclopropanes. The relaxation time of both proton and carbon are slightly affected by the size of substituents. In the viscosity study, an inverse‐law relationship between relaxation time and viscosity was observed.     

Synthesis of Functionalized Bicyclic Compounds Based on 2-(1-Arylethylidene)malononitriles

Russian Journal of Organic Chemistry - New tetrahydroisoquinoline-5,7-dicarbonitrile derivatives have been synthesized by piperazine hydrate-catalyzed reaction of acetoacetanilide with...     

Regioselective synthesis of highly-substituted biaryls by reaction of vinyl malononitriles with acetylenic esters

The one-pot procedure for synthesis of highly-substituted biaryl derivatives has been described via cyclocondensation reaction between vinyl malononitriles and acetylenic esters. A series of complex biaryls containing one-donor and three-acceptor moieties was obtained with good yields.     

Highly enantioselective Michael/cyclization tandem reaction between dimedone and isatylidene malononitriles

A highly enantioselective Michael/cyclization tandem reaction between dimedone and isatylidene malononitriles has been developed. With 5?mol% of bifunctional organocatalyst C15, chiral spiro[2-amino-4H-pyran-oxindole] derivatives were obtained in excellent yields (97–99%) with excellent enantioselectivities (up to?>?99% ee).     

Synthesis of 2-(4H-1,2,6-thiadiazin-4-ylidene)malononitriles

The base-free TiCl₄-mediated condensation of 3,5-disubstituted-4H-1,2,6-thiadiazin-4-ones 8 with malononitrile affords 20 difficult to access (3,5-disubstituted-4H-1,2,6-thiadiazin-4-ylidene)malononitriles 7. The reaction tolerates 3,5-diaryl, diphenoxy, dimethoxy and diphenylthio substituted thiadiazinones, but not diamino, monohydroxy or dihalo substituents. Nevertheless, asymmetrically substituted 3-halo-5-phenyl- and 3-chloro-5-methoxy-4H-1,2,6-thiadiazin-4-ones convert into the corresponding ylidenemalononitriles in good yield. Furthermore, the condensation works well with ethyl cyanoacetate and diethyl malonate, but not with Meldrum's acid, dimedone or nitromethane. Finally, 2-(3-chloro-5-phenyl-4H-1,2,6-thiadiazin-4-ylidene)malononitrile (7q) reacts with aniline to give 4,7-diphenyl-6-(phenylimino)-6,7-dihydropyrrolo[2,3-c][1,2,6]thiadiazine-5-carbonitrile (12) in moderate yield demonstrating the potential use of these ylidenes to prepare novel 6–5 fused 4H-1,2,6-thiadiazines.     

Equilibrium geometry and electronic structure of benzylidene,arylethylidene, and heterocyclic arylidene malononitriles

The equilibrium geometry of some benzylidene, arylethylidene, and heterocyclic arylidene malononitriles has been calculated within the framework of the MNDO –MO formalism. Various structural factors are analyzed and discussed in terms of localized and delocalized MOS and π-interaction between methylene malononitrile (MMN) and aryl moieties. The possibility of charge transfer (CT ) from aryl to MMN moieties has been examined. The presence of a heterocyclic ring introduces a small perturbation into the MMN nuclear frame. p-Substituents have a pronounced effect on the magnitude and direction of the dipole moment. The variation of ionization potentials and bond order with the Hammet σ p are examined and a straight-line relationship is obtained. The correlation between physiological activity and quantum mechanical properties is analyzed in terms of heat of formation, ionization potential, dipole moment, and charge density on the aryl ring. © 1994 John Wiley & Sons, Inc.     

Efficient method for the synthesis of polysubstituted benzenes by one-pot tandem reaction of vinyl malononitriles with nitroolefins

The one-pot synthesis of polysubstituted benzene derivatives was achieved via vinylogous Michael addition of vinyl malononitriles and nitroolefins as the key step and a sequential tandem reaction. A series of complex aryl compounds such as biphenyls and terphenyls can be obtained with satisfactory yields.     

Synthesis of 2-[5-amino-2,3-dihydro-4H-imidazol-4-ylidene]malononitriles

Using the system of tetracyanoethylene, ammonium acetate and a carbonyl compound, the preparation of 2-[5-amino-2,3-dihydro-4H-imidazol-4-ylidene]malononitriles was carried out. The structures of these new dihydroimidazoles were determined by NMR experiments and by X-ray crystallography.     

Nitrileketenimine tautomerism in substituted alkylidene malononitriles and alkylidene cyanoacetates: A characteristic UV absorption band

Several alkylidene malononitriles (1b,1d,1e,2b and4b) and alkylidene cyanoacetates (1a,2a and4a) studied exhibit a long wavelength UV absorption band around 355 nm which shows a hyperchromic effect in the presence of ethanolic alkali. This band has been assigned to the ketenimine tautomer (5). Addition of water to1b,1e and2b gives the corresponding pyridine diols (7a,7b and8a) respectively. Similarly, addition of ethanol to1e and2b gave the corresponding ethoxypyridine derivatives (7c and8b). Mechanism of formation of these compounds is discussed. Structures, as well as mechanism of formation of1c,7c and10 obtained from1b,1e and2b respectively on standing at room temperature are also discussed.     

Normal coordinate analysis of malononitriles: III. The valence force field of malononitrile and its deuterated derivatives

The procedure of Becher and Mattes [1] has been applied to the calculation of the valence force field for malononitrile H₂C(CN)₂ and its deuterated derivatives, HDC(CN)₂ and D₂C(CN)₂. The results have been localized in the space of the real solutions of the inverse vibrational eigenvalue problem. The convergence of the method has been demonstrated. The average deviation between observed and calculated frequencies on isotopic substitution is less than 1 %.     

Efficient synthesis of multicyclic spirooxindoles via a cascade Michael/Michael/oxa-Michael reaction of curcumins and isatylidene malononitriles

A cascade Michael/Michael/oxa-Michael reaction between curcumins and isatylidene malononitriles has been developed. Multicyclic spirooxindoles were prepared in excellent yields and diastereoselectivities. DMAP was found to catalyze this transformation efficiently under mild reaction conditions.     

Highly regio- and diastereoselective construction of spirocyclopenteneoxindoles through phosphine-catalyzed [3 + 2] annulation of Morita-Baylis-Hillman carbonates with isatylidene malononitriles

Phosphine-catalyzed highly regio- and diastereoselective [3 + 2] annulation of Morita-Baylis-Hillman (MBH) carbonates with isatylidene malononitriles has been disclosed to give the corresponding spirocyclopenteneoxindoles in excellent yields under mild conditions. A plausible reaction mechanism has also been proposed on the basis of previous literature.     

Synthesis and characterization of 2-(4-aryl-3-cyano-6-methylpyridin-2(1H)-ylidene)malononitriles

The synthesis of pyridine derivatives containing a buta-1,3-diene-1,1,3-tricarbonitrile fragment via the base-promoted reaction of benzalacetones and malononitrile dimer with subsequent oxidation is described. The influence of the substituents on the spectral-luminescent and electrochemical properties was also investigated.