Nitration of alcohols by nitryl fluoride

A general method for the preparation of nitrates by treatment of alcohols with nitryl fluoride (FNO₂) in MeCN in the presence of KF has been developed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1059–1060, May, 1997.     

Carbolithiation of substituted stilbenes and styrenes with dithianyllithiums

Carbolithiation of a range of substituted stilbenes and styrenes with dithianyllithiums is described, leading to the rapid, efficient and stereocontrolled assembly of highly functionalized dithiane intermediates for acyl-equivalents synthesis.     

Nitration of substituted chromans

The nitration of substituted chromans has been studied and the structure of the nitro compounds has been confirmed by chemical and spectral data.     

Phenyliodonium diacetate mediated arylation of benzothiazoles with substituted styrenes

A metal-free synthesis of 2-arylbenzothiazoles was achieved using phenyliodonium diacetate (PIDA) from benzothiazoles and styrenes or β-nitrostyrenes. This transformation tolerates various functional groups such as methoxy, hydroxy, fluoro, chloro, and nitro groups.     

Torsions in conjugated aromatics: substituted styrenes

The low frequency torsional overtone (Δ v = 2) of the vinyl group has been observed in the gas phase Raman spectra of m- and p-fluorostyrene, m- and p-chlorostyrene and p-methylstyrene. The calculated barriers to internal rotation are all slightly smaller than that forstyrene itself. It appears that canonical structures, consistent with the conventional resonance arguments used to explain the reactions of para-substituted aromatics, play little or no role in the ground electronic states of these substituted styrenes. The slight downward trend in the barrier heights may be explained in terms of a small increase in the steric forces at the planar conformation.     

Reactions of arylnitroso oxides with substituted styrenes: Kinetics and products

The kinetics of the reactions of phenylnitroso oxide and 4-CH₃O- and 4-Cl-phenylnitroso oxides with a series of substituted styrenes (4-X-C₆H₄-CH=CH₂; X = H, CH₃O, Cl, CN) in acetonitrile at 22 ± 2°C was studied using the flash photolysis technique. It was shown for 4-CH₃O-C₆H₄NOO as an example that only the trans isomers of the nitroso oxides are involved in the reaction. There is a linear correlation between the logarithm of the rate constant and the electronic properties of the substituent in the nitroso oxide aromatic ring on the Hammett scale: ρ = 2.3 ± 0.3 (r = 0.993) for 4-CH₃O-styrene ρ = 2.03 ± 0.07 (r = 0.995) for styrene, and ρ = 1.77 ± 0.05 (r = 0.9996) for 4-Cl-styrene. Both the electron-donating and electron-withdrawing substituents in the aromatic ring of styrene increase its reactivity toward a given nitroso oxide. An analysis of the products of phenyl azide photooxidation in the presence of styrene showed that the product of phenylnitroso oxide [3+2]cycloaddition to the double bond of the olefin decomposes into benzalaniline and carbonyl oxide.     

Substituent effects in free radical copolymerization of substituted styrenes with acrylates and methacrylates

Relative reactivity ratios have been determined for o-chlorostyrene with five lower acrylates and methacrylates, respectively, and for methyl acrylate with a number of substituted styrenes in free-radical copolymerization. Analysis of the data shows that: (a) acrylates are less reactive than methacrylates with o-chlorostyrene; (b) length of the side chain has little or no effect in methacrylates, but its effect is pronounced in acrylates with respect to their reactivity ratios; (c) chlorine substitution in the side chain of either acrylates or methacrylates has a significant influence on the reactivity ratio; (d) relative reactivity ratio data for methyl acrylate with substituted styrenes fail to show the expected relationship between monomer structure and resonance theory, inductive effect and, consequently, the Hammett σ values.     

Generation of substituted styrenes via Suzuki cross-coupling of aryl halides with 2,4,6-trivinylcyclotriboroxane

The synthesis of functionalized styrene derivatives can be readily achieved utilizing a Suzuki cross-coupling protocol between aryl halides and 2,4,6-trivinylcyclotriboroxane-pyridine complex. The scope and limitations of the procedure were demonstrated by investigation of an array of ortho-substituted aryl halides.     

Methoxychlorination and dimethoxylation of alkenes the reactions of substituted styrenes with phenylselenenyl chloride in methanol

The addition of PhSeCl to α- and β-substituted styrenes in methanol is regio- and stereospecific and affords the products of methoxyselenenylation. These compounds further react with PhSeCl to give the deselenenylation products. In the case of α-substituted styrenes, 1-methoxy, 2-chloroalkanes are produced, whereas with β-substituted styrenes the major reaction products are the 1,2-dimethoxyalkanes and the 2,2-dimethoxyalkanes in which phenyl migration has occurred. It is shown that these reactions proceed through the intermediate formation of the alkyi phenylselenium dichlorides, PhCR(OMe)CHR₁SeCl₂Ph, which evolve with different mechanisms depending on the structure of the starting alkenes.     

Conformational isomerizations of symmetrically substituted styrenes. No-reaction photoreactions by Hula-twist

Symmetrically substituted styrenes photochemically gave unstable conformers in low temperature organic glass in a manner consistent with the recently postulated Hula-twist mechanism of photoisomerization.     

One-pot synthesis of substituted styrenes from vicinal dibromoalkanes and arylboronic acids

Dehydrobromination of vicinal dibromoalkanes in systems comprising 1,2-dimethoxy-ethane, N-butyl-N′-methylimidazolium tetrafluoroborate (or tetrabutylammonium bromide), and a base with subsequent palladium-catalyzed cross-coupling of the thus formed bromoalkenes with arylboronic acids furnished substituted styrenes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 116–123, January, 2007.     

Spontaneous reactions of electron‐accepting substituted quinodimethane with substituted styrenes: Inductive and steric effects on the formation of a zwitterionic intermediate

Spontaneous reactions of an electron‐accepting substituted quinodimethane, 1‐(2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione‐5‐ylidene)‐4‐(dicyanomethylene)‐2,5‐cyclohexadiene, with p‐substituted, α‐substituted, and β‐substituted styrenes were investigated. When p‐substituted styrenes were used as comonomers, no spontaneous reactions took place for styrenes with an electron‐accepting p substituent such as COOMe and CN groups, and both terpolymers and cycloadducts were formed for the other p‐substituted styrenes. When α‐substituted and β‐substituted styrenes were used as comonomers, no reactions occurred for α‐ and β‐substituted styrenes with a bulky phenyl group, and spontaneous reactions took place for those with a smaller methyl group. The reaction products were an alternating copolymer for α‐substituted styrene and both terpolymers and 5‐ethylidene‐2,5‐dimethyl‐1,3‐dioxane‐4,6‐dione for β‐substituted styrenes. The position of the methyl group in the styrenes significantly affected the product formation. This behavior in the spontaneous reactions was discussed on the basis of the ability of formation of the zwitterionic tetramethylene intermediate and its conformation, determined by polar and steric effects of the substituents in the substituted styrenes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5195–5206, 2005     

Reaction of 1,3-dicarbonyl compounds with nitryl chloride

Reaction of 1,3-dicarbonyl compounds with nitryl chloride through substitution on the activated methylene group, resulted in the formation of chloro, dichloro and oximino derivatives.

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Die Reaktion der 1,3-Dicarbonylverbindungen mit Nitrylchlorid

Zusammenfassung Umsetzung von 1,3-Dicarbonylverbindungen mit Nitrylchlorid ergab die entsprechende Chloro-, Dichloro- und Oximinoderivate in einer Substitutionsreaktion an der aktivierten Methylengruppe.