Investigation of the dynamic equilibrium between 2-(dialkylboryl)-1-methylenecyclobutane and 1 - ((dialkylboryl) methyl)-1-cyclobutene

Ilya Gridnev, M. E. Gursky, Yu N. Bubnov

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The reaction of potassium methylenecyclobutanide with dibutylboron chloride and 9-bromo-9-borabicyclo[3.3.1]nonane yields the corresponding allylic type triorganoboranes 1 and 2. Compounds 1 and 2 exhibit a facile [1,3]-B sigmatropic shift, which results in the reversible coexistence of isomeric 2-(dialkylboryl)-1-methylenecyclobutanes 1a and 2a with 1-((dialkylboryl)methyl)-1-cyclobutenes 1b and 2b. For both compounds 1 and 2, the 2-(dialkylboryl)-1-methylenecyclobutane form (1a, 2a) is predominant at low temperatures, while raising the temperature leads to a shift of the equilibrium in favor of the 1-((dialkylboryl)methyl)-1-cyclobutene form (1b, 2b). Activation parameters for the equilibrium in 1 were found from the 2D 13C-13C spectra (for the transformation 1a → 1b Eact = 35.5 ± 2.5 kJ mol-1, ΔG ± 298 = 53.8 ± 0.5 kJ mol-1; for the transformation 1b -1a Eact = 33.8 ± 2.5 kJ mol-1, ΔG ± 298 = 52.8 ± 0.5 kJ mol-1). For the equilibrium in 2, the rate constants of the direct and reverse reaction were determined at 180 K (k2a2b = 0.30 ± 0.03 s-1, k2b2a = 6.3 ± 0.3 s-1).

Original languageEnglish
Pages (from-to)3696-3702
Number of pages7
JournalOrganometallics
Volume15
Issue number17
DOIs
Publication statusPublished - 1996 Aug 20
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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