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

Authors

  • Mikhail Yu. Ovchinnikov,

    Corresponding author
    • Institution of Russian Academy of Sciences Institute of Organic Chemistry, Ufa Scientific Centre of the Russian Academy of Sciences, Ufa, Russian Federation
    Search for more papers by this author
  • Tagir A. Yangirov,

    1. Institution of Russian Academy of Sciences Institute of Organic Chemistry, Ufa Scientific Centre of the Russian Academy of Sciences, Ufa, Russian Federation
    Search for more papers by this author
  • Alexander N. Lobov,

    1. Institution of Russian Academy of Sciences Institute of Organic Chemistry, Ufa Scientific Centre of the Russian Academy of Sciences, Ufa, Russian Federation
    Search for more papers by this author
  • Rimma M. Sultanova,

    1. Institution of Russian Academy of Sciences Institute of Organic Chemistry, Ufa Scientific Centre of the Russian Academy of Sciences, Ufa, Russian Federation
    Search for more papers by this author
  • Sergey L. Khursan

    1. Institution of Russian Academy of Sciences Institute of Organic Chemistry, Ufa Scientific Centre of the Russian Academy of Sciences, Ufa, Russian Federation
    Search for more papers by this author

  • Contract grant sponsor: Federal Targeted Program “Scientific and Scientific-Pedagogical Personnel of the Innovative Russia” in 2009-2013 (agreement 8175).

  • Supporting Information is available in the online issue at www.wileyonlinelibrary.com.

Correspondence to: Mikhail Yu. Ovchinnikov; e-mail: myuovchinnikov@gmail.com.

ABSTRACT

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 k1t and k1c. 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 (k2t, k2c) and 1Н-pyrazoline concentrations (k3t, k3c). 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): k1t = 2.3 ± 0.3, k1c = 1.6 ± 0.2, k2t = 1.1 ± 0.3, k2c = 1.8 ± 0.5, k3t = 1.2 ± 0.4, k3c = 2.2 ± 0.7.

Ancillary