Generation of 1,2-azaboretidines via reduction of ADC borane adducts
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Authors: | H. Braunschweig A. Gackstatter T. Kupfer T. Scheller F. Hupp A. Damme N. Arnold W. C. Ewing |
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Affiliation: | a Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . Email: ; http://www-anorganik.chemie.uni-wuerzburg.de/Braunschweig/ |
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Abstract: | Reaction of the acyclic (diamino)carbene (ADC) :C(NiPr2)2 (1) with different dihaloboranes of the type RBX2 (R = Mes, Dur; X = Cl, Br) smoothly afforded a novel class of ADC-stabilized borane adducts. For MesBBr2 however, the reaction did not stop at the adduct level, but an uncommon rearrangement process occurred, which eventually resulted in the formation of a 5-membered boracycle after elimination of mesitylene. Chemical reduction of the ADC borane adducts by KC8 selectively yielded air stable 1,2-azaboretidines. Detailed DFT studies suggest a reduction mechanism involving a highly reactive borylene intermediate, which is converted into the boracycles via a rearrangement/C–H activation sequence. |
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