331432-75-8Relevant academic research and scientific papers
Syntheses and reactivity of exocyclic unsaturated heterodiborolanes and their diborylhexadiene precursors - Formation of 2-Aza-4,5-dicarba-nido-hexaboranes(6)
Greiwe, Peter,Beez, Volker,Pritzkow, Hans,Siebert, Walter
, p. 381 - 386 (2007/10/03)
The aryl-substituted 3,4-diboryl-2,4-hexadienes 4c-e are generated when 3,4-bis(dimethoxyboryl)-2,5-dimethyl-2,4-hexadiene (4a) and 3,4-bis(dichloroboryl)-2,5-dimethyl-2,4-hexadiene (4b) react with two equivalents of xylyllithium or duryllithium. Cyclization reactions of 4b with heptamethyldisilazane and of 4c with MeN(SiMe3)2, S(SiMe3)2, and O(SiMe3)2 lead to the corresponding 2,5-diaryl-3,4-diisopropylidene-1-hetero-2,5-diborolanes 5a,b, 6, and 7 in excellent yields. 1-Aza-2,5-di-tert-butyl-3,4-diisopropylidene-1-methyl-2,5-diborol ane (5c) is obtained from the reaction of 5a with two equivalents of tert-butyllithium. When the azadichlorodiborolane 5a is reacted with Li[BH4] or Li[DurBH3] the Cl atoms are replaced by hydrogen or duryl and the liberated BH3 hydroborates the isopropylidene groups to form the 2-Aza-4,5-dicarba-4,5-diisopropyl-2-methyl-nido-hexaboranes 10a,b. The new compounds are characterized by MS and 1H, 11B and 13C NMR spectroscopy. X-ray structure analyses of 4c and 4e show that the two halves of the hexadienes are rotated by 80 to 90°. The solid state structures of the three duryl-substituted heterodiborolanes 5b, 6, and 7 reveal twist conformations of the C2B2X rings.
