Brønsted Acid TfOH-Mediated Reactions of Methylenecyclopropanes with Nitriles

Abstract

In the presence of Brønsted acid TfOH, methylenecyclopropanes react with nitriles to give [3+2] cycloaddition products in good to high yields along with Ritter reaction products. In many cases, [3+2] cycloaddition products are obtained as the major products. The reaction conditions have been carefully examined and the plausible mechanism has been proposed.

Key words

methylenecyclopropanes - Brønsted acid - acetonitrile - benzonitrile - [3+2] cycloaddition - Ritter reaction

References

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5

This is because some MCPs 1 such as MCPs 1b and 1c are not very soluble in MeCN and the co-solvent CH₂Cl₂ is therefore required.

6

The crystal data of 3a has been deposited in CCDC with number 219397. Empirical Formula: C₁₈H₁₇N; formula weight: 247.33; crystal color, habit: colorless, prismatic; crystal dimensions: 0.433 × 0.357 × 0.258 mm; crystal system: monoclinic; lattice type: primitive; lattice parameters: a = 23.589 (3)Å, b = 7.8691 (11)Å, c = 18.498 (3)Å, α = 90^o, β = 127.366 (2)^o, γ = 90^o, V = 2729.0(6)ų; space group: C2/c; Z = 8; D _calc = 1.204 g/cm³; F ₀₀₀ = 1056; diffractometer: Rigaku AFC7R; residuals: R, Rw: 0.0432, 0.0784.

7

Benzonitrile is used as the reactant and the solvent because many MCPs 1 are dissolved very well in benzonitrile.