Synthesis and Characterization of New Boron Compounds Using Reaction of Diazonium Tetraphenylborate with Enaminoamides

Markéta Svobodová; Jan Svoboda; Bing-Han Li; Valerio Bertolasi; Luboš Socha; Miloš Sedlák; Lukáš Marek

doi:10.3390/molecules27020367

Synthesis and Characterization of New Boron Compounds Using Reaction of Diazonium Tetraphenylborate with Enaminoamides

Molecules. 2022 Jan 7;27(2):367. doi: 10.3390/molecules27020367.

Authors

Markéta Svobodová¹, Jan Svoboda¹, Bing-Han Li², Valerio Bertolasi³, Luboš Socha¹, Miloš Sedlák¹, Lukáš Marek¹

Affiliations

¹ Faculty of Chemical Technology, Institute of Organic Chemistry and Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic.
² Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan.
³ Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via L. Borsari 46, 44121 Ferrara, Italy.

Abstract

A family of oxazaborines, diazaborinones, triazaborines, and triazaborinones was prepared by reaction of polarized ethylenes, such as β-enaminoamides, with 4-methylbenzenediazonium tetraphenylborates. The reaction conditions (stirring in CH₂Cl₂ at room temperature (Method A) or stirring with CH₃COONa in CH₂Cl₂ at room temperature (Method B) or refluxing in the CH₂Cl₂/toluene mixture (Method C)) controlled the formation and relative content of these compounds in the reaction mixtures from one to three products. Substituted oxazaborines gradually rearranged into diazaborinones at 250 °C. The prepared compounds were characterized by ¹H NMR, ¹³C NMR, IR, and UV-Vis spectroscopy, HRMS, or microanalysis. The structure of individual compounds was confirmed by ¹¹B NMR, ¹⁵N NMR, 1D NOESY, and X-ray analysis. The mechanism of reaction of enaminoamides with 4-methylbenzenediazonium tetraphenylborate was proposed.

Keywords: boron; diazaborinone; enaminoamide; oxazaborine; triazaborine; triazaborinone.