Boron-nitrogen compounds: XCVI. Studies of the chemical behavior of monomeric pyrazol-1-ylboranes |
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Authors: | Fazlul Alam Kurt Niedenzu |
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Institution: | Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506 U.S.A. |
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Abstract: | Two 1,3-dimethyl-2-(methylpyrazol-1′-yl)-1,3,2-diazaboracyclopentanes have been prepared. The interaction of such monomeric pyrazol-1-ylboranes containing trigonal boron with pyrazoles has been examined and molar addition compounds have been identified and isolated. Labelling experiments support spectroscopic evidence to suggest a mobile bridging hydrogen in the cited adducts at ambient temperature and above. Monomeric 1,3-dimethyl-2-(pyrazol-1′-yl)-1,3,2-diazaboracyclopentane reacts with (dimethylamino)dialkylboranes by an exchange of the pyrazolyl with the dimethylamino group. A cyclic transition state involving a B2N3 ring system is suggested for this process in which the corresponding 2-dimethylamino-1,3,2-diazaboracyclopentane and B-tetraalkylpyrazaboles are the final products. The latter are also found among the reaction products of pyrazole adducts of monomeric pyrazol-1-ylboranes with (dimethylamino)dialkylboranes. The interaction of (dimethylamino)dialkylboranes with pyrazole gives B-tetraalkylpyrazaboles in essentially quantitative yield. |
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Keywords: | To whom coorespondence should be addressed |
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