Cu(OAc)2-2,4-lutidine-ZnCl2 as an effective catalyst of functionalization of isobutylene oligomers and 1,2-polybutadiene with methyl diazoacetate

The possibility of [1+2]-cycloaddition of methoxycarbonylcarbene generated by catalytic decomposition of methyl diazoacetate in the presence of the Cu(OAc)₂-2,4-lutidine-ZnCl₂ system to the carbon-carbon double bound in isobutylene oligomers and syndiotactic 1,2-polybutadiene was examined. A comparative analysis of physicochemical properties of the starting compounds and their functionalized products was performed.     

Phosphazenes: I. Reactions with electron-deficient alkenes

Triphenylphosphazenes reacted with methyl vinyl ketone, methyl acrylate, methyl methacrylate, and dimethyl maleate to give the corresponding substituted dihydropyrazoles.     

Synthesis and properties of cyclopropane derivatives of polybutadienes

Polymer products containing methoxycarbonyl-substituted cyclopropane groups in macromolecules with degrees of functionalization up to 40% have been obtained through the interaction of polybutadiene with methyl diazoacetate in an organic solvent in the presence of an organometallic catalyst. The comparative catalyst activity in the reaction of cyclopropanation of polybutadiene has been estimated. The incorporation of methoxycarbonyl-substituted cyclopropane groups into polydiene units results in substantial changes in the polymer properties: solution viscosity, melt flow, glass-transition temperature, and thermal stability.     

Copoly(arylene phthalides) in the thermal polymerization of styrene

Russian Chemical Bulletin - The thermal polymerization of styrene in the presence of polymer initiators, copoly(arylene phthalides) of the diphenyl oxide series with different ratios of two...     

The rotameric (R*,S*)- and (R*,R*)-biaryl-3,3′-diphthalides of polyphenylene series

A wide range of diastereomeric pairs of biaryl-3,3′-diphthalides with aromatic (heteroaromatic) substituents of polyphenylene series (including halogen substituted) was synthesized. All of them were separated and characterized by the methods of X-ray analysis, HPLC, IR-, 1H and 13C NMR spectroscopy. It was determined that solubility, tendency to adsorption and related to it retention times, chemical shifts of equivalent hydrogen and carbon atoms of biaryl-3,3′-diphthalides diastereoisomers are determined firstly by the stereo-electronic effects of two adjacent strongly polar phthalide groups. It was shown that both in crystalline phase and in solution all the diphthalides, regardless of the chemical structure of their substituents, are existing as stable rotamers with cis or synperiplanar (chiral forms) and trans or antiperiplanar (meso-forms) conformation.     

1,3‐Dipolar Cycloaddition of Diazo Compounds to Electron‐Deficient Alkenes: Kinetics and Mechanism of Formation of Dimethyl‐4,5‐dihydro‐1H‐pyrazol‐3,5‐dicarboxylate

1,3‐Dipolar cycloaddition of methyl diazoacetate to methyl acrylate was investigated by kinetic ¹Н NMR spectroscopy. It was established that the mechanism of the process includes parallel formation of trans‐ and cis‐dimethyl‐4,5‐dihydro‐3H‐pyrazol‐3,5‐dicarboxylates as a result of [3 + 2]‐cycloaddition of methyl diazoacetate to methyl acrylate; the corresponding rate constants were denoted k_1t and k_1c. The reaction rate of the isomerization of 3Н‐pyrazolines to 4,5‐dihydro‐1H‐pyrazol‐3,5‐dicarboxylate (3Н → 1Н‐pyrazoline rearrangement) was found to be sensitive to both the methyl acrylate (k_2t, k_2c) and 1Н‐pyrazoline concentrations (k_3t, k_3c). Kinetic analysis showed that the proposed scheme is valid for various reagent concentrations. The numerical solution of the system of differential equations corresponded to the reaction scheme and was used to determine the complete set of reaction rate constants (k (× 10⁵ M^–1·s^–1), 298 K; solvent, benzene‐d₆): k_1t = 2.3 ± 0.3, k_1c = 1.6 ± 0.2, k_2t = 1.1 ± 0.3, k_2c = 1.8 ± 0.5, k_3t = 1.2 ± 0.4, k_3c = 2.2 ± 0.7.     

Ni(0)-Catalyzed Dimerization of o-Keto Carboxylic Acid Pseudochlorides

Russian Journal of Organic Chemistry - A new protocol of the synthesis of 3,3′-diaryl-3,3′-diphthalides by dehalogenation of o-keto carboxylic acid pseudochlorides is implemented. The...