14695-69-3Relevant articles and documents
Catalyzed reaction of triethylborane with pyrazole
Dabrowski, Marek,Luliński, Sergiusz,Madura, Izabela,Serwatowski, Janusz,Zachara, Janusz
, p. 190 - 195 (2000)
The reaction of triethylborane with pyrazole leading to 4,4,8,8-tetraethylpyrazabole was found to be catalyzed by carboxylic acids. 2,2′-Dimethylpropanoic (pivalic) or benzoic acids act as catalysts in this reaction. Intermediates occurring in the catalyt
Novel Substituted B2ElVIN2 Heterocycles
Yalpani, Mohamed,Koester, Roland,Boese, Roland
, p. 19 - 24 (2007/10/02)
The bis(diorganoboryl) chalcogenides (R2B)2O , (R2B)2S , and (R2B)2Se react with pyrazole (Pz) and its derivatives 3-methylpyrazole (3-MePz) and indazole (benzo-Pz) to form in high yields (65 - 92 percent) stable 1 : 1 adducts . 1H-, 13C-, 11B-NMR spectra and X-ray analyses (of 2 and 6) show a basic structure with a central B2ElN2 (El = O, S, Se) heterocycle.The reaction of 2 with R2BH and the thermolysis of 4 give the dimeric 1-pyrazolylboranes 9a and 9b, respectively. -Keywords: Bis(diorganoboryl)chalcogenides / Pyrazaboles / Pyrazoles
Boron-nitrogen compounds. 110. Reactions of boroxins and diboroxanes with pyrazole
Bielawski,Niedenzu
, p. 1771 - 1774 (2008/10/08)
Tetraorganyldiboryl oxides (1,3-diboroxanes) (R2B)2O (R = C2H5, C6H5), react at elevated temperatures with excess pyrazole, Hpz, to give an essentially quantitative yield of the corresponding pyrazabole, R2B(μ-pz)2BR2. The 1,3-diboroxane [(CH3)2NBR]2O (R = C6H5) reacts with Hpz in refluxing toluene to form the triply bridged pyrazabole RBB(μ-pz)2(μ-OBRO)BR as the major product besides substantial quantities of the diboroxane derivative [(pz)RB(μ-pz)2BR]2O. In the latter, two pyrazabole moieties are linked by an oxygen bridge between boron atoms. The boroxin adduct (-BRO-)3·Hpz (R = C6H5) is obtained on direct interaction of triphenylboroxin with pyrazole at room temperature. As based on NMR data, two boron atoms of the boroxin ring are coordinated to pyrazole nitrogen atoms and the N-bonded proton is delocalized. In contrast, all three boron atoms are coordinated in 1:1 molar mixtures of the boroxin with either 3,5-dimethylpyrazole or imidazole. The adduct (-BRO-)3·3Hpz was identified as a transient species. It undergoes a slow condensation on standing in solution at room temperature. At elevated temperatures the reaction progresses readily to yield the triply bridged pyrazabole RB(μ-pz)2(μ-OBRO)BR. When a neat mixture of the two reagents is refluxed, the pyrazabole R2B(μ-pz)2BR2 is obtained. Triethylboroxin and pyrazole interact readily even at room temperature beyond mere complexation to form RB(μ-pz)2(μ-OBRO)BR with R = C2H5. Additional pyrazole and even minor increases in temperature promote the condensation process.