Generation of 1, 2-azaboretidines via reduction of ADC borane adducts. Issue 6 (24th April 2015)

• Record Type: Journal Article
• Authors: Braunschweig, H.; Gackstatter, A.; Kupfer, T.; Scheller, T.; Hupp, F.; Damme, A.; Arnold, N.; Ewing, W. C.
• Is Part Of: Chemical science. Volume 6:Issue 6(2015:Jun.)
• Page Start: 3461
• Page End: 3465
• Publication Date: 2015-04-24
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c5sc01077b
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : ADC borane adducts RBX2 ·ADC (R = Mes, Dur; X = Cl, Br; ADC = :C(NiPr2 )2 ) have been prepared and reduced by KC8 to afford air stable 1, 2-azaboretidines with high selectivity. 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.