148892-98-2Relevant academic research and scientific papers
Sequential C?H Borylation and N-Demethylation of 1,1′-Biphenylamines: Alternative Route to Polycyclic BN-Heteroarenes
Zhang, Jianbo,Jung, Hoimin,Kim, Dongwook,Park, Sehoon,Chang, Sukbok
supporting information, p. 7361 - 7365 (2019/04/30)
Described herein is an unprecedented access to BN-polyaromatic compounds from 1,1′-biphenylamines by sequential borane-mediated C(sp2)?H borylation and intramolecular N-demethylation. The conveniently in situ generated Piers’ borane from a borinic acid reacts with a series of N,N-dimethyl-1,1′-biphenyl-2-amines in the presence of PhSiH3 to afford six-membered amine-borane adducts bearing a C(sp2)?B bond at the C2′-position. These species undergo an intramolecular N-demethylation with a B(C6F5)3 catalyst to provide BN-isosteres of polyaromatics. According to computational studies, a stepwise ionic pathway is suggested. Photophysical characters of the resultant BN-heteroarenes shown them to be distinctive from those of all-carbon analogues.
Selective C?O Bond Cleavage of Sugars with Hydrosilanes Catalyzed by Piers’ Borane Generated In Situ
Zhang, Jianbo,Park, Sehoon,Chang, Sukbok
supporting information, p. 13757 - 13761 (2017/10/09)
Described herein is the selective reduction of sugars with hydrosilanes catalyzed by using Piers’ borane [(C6F5)2BH] generated in situ. The hydrosilylative C?O bond cleavage of silyl-protected mono- and disaccharides in the presence of a (C6F5)2BH catalyst, generated in situ from (C6F5)2BOH, takes place with excellent chemo- and regioselectivities to provide a range of polyols. A study of the substituent effects of sugars on the catalytic activity and selectivity revealed that the steric environment around the anomeric carbon (C1) is crucial.
The Propargyl Rearrangement to Functionalised Allyl-Boron and Borocation Compounds
Wilkins, Lewis C.,Lawson, James R.,Wieneke, Philipp,Rominger, Frank,Hashmi, A. Stephen K.,Hansmann, Max M.,Melen, Rebecca L.
supporting information, p. 14618 - 14624 (2016/10/03)
A diverse range of Lewis acidic alkyl, vinyl and aryl boranes and borenium compounds that are capable of new carbon–carbon bond formation through selective migratory group transfer have been synthesised. Utilising a series of heteroleptic boranes [PhB(Cs
A comparative study of base-free arylcopper reagents for the transfer of aryl groups to boron halides
Sundararaman, Anand,J?kle, Frieder
, p. 134 - 142 (2007/10/03)
A comparative study on the reactivity and selectivity of arylcopper species in reactions with boron halides was performed. Mesitylcopper reacts with BX3 (X=Cl, Br) in toluene at low temperature under highly selective formation of the monosubstituted boranes MesBX2. The dimesitylboranes Mes2BX are gradually formed with a twofold excess of the organocopper reagent at elevated temperature. In contrast, pentafluorophenylcopper shows a tendency for formation of B(C6F5) 3 in reactions with BX3 irrespective of the stoichiometry used, suggesting a strong impact of electronic factors on the selectivity of the aryl transfer reaction. New procedures for the synthesis of the pentafluorophenylboron halides C6 F5BX2 (X=Cl: 57%; X=Br: 62%) and of tris(pentafluorophenyl)borane (80%) and related mixed-substituted triarylboranes from the base-free isolable pentafluorophenylcopper precursor have been developed.
Highly electrophilic olefin polymerization catalysts. Quantitative reaction coordinates for fluoroarylborane/alumoxane methide abstraction and ion-pair reorganization in group 4 metallocene and 'constrained geometry' catalysts
Deck, Paul A.,Beswick, Colin L.,Marks, Tobin J.
, p. 1772 - 1784 (2007/10/03)
Reaction enthalpies of group 4 metallocenes having the general formula L2M(CH3)2 (L = Cp, 1,2-Me2Cp, Me5Cp; L2 = Me2Si(Me4Cp)((t)BuN); M = Ti, Zr, and Hf) with the strong organo-Lewis acid B(C6F5)3 were measured using batch titration calorimetry in toluene. Methide abstraction to form the corresponding L2MCH3+CH3B(C6F5)3- contact ion pairs is highly exothermic in all cases. Exothermicity increases with increasing Cp methyl substitution: for M = Zr, ΔH = -23.1(3), -24.3(4), and -36.7(5) kcal mol-1 for L = Cp, Me2Cp, and Me5Cp, respectively for M = Hf and L = 1,2-Me2Cp, ΔH = -20.8(5) kcal mol-1. 'Constrained geometry' complexes (L2 = Me2Si(Me4Cp)((t)BuN)) exhibit similar exothermicities, with ΔH = -22.6(2), -23.9(4), and -19.3(6) kcal mol-1 for M = Ti, Zr, and Hf, respectively. In contrast, analogous reactions with methylalumoxane (M:Al = 1:50) are less exothermic, with ΔH = -10.9(3) and -8.9(4) kcal mol-1 for L = 1,2-Me2Cp and M = Zr and Hf, respectively. Under identical conditions, (1,2-Me2Cp)2M-(CH3)2 (M = Zr, Hf) complexes also undergo methide abstraction with the less Lewis-acidic triarylboranes (C6F5)2BAr (AT = 3,5-C6H3F2, Ph, and 3,5-C6H3Me2); however, conversions to the corresponding (Me2-Cp)2MCH3+ CH3B(C6F5)2Ar- ion pairs, are incomplete. Variable-temperature NMR measurements yield thermodynamic parameters for partial methide abstraction by these less Lewis-acidic boranes. For Ar = 3,5-C6H3F2, ΔH = -18.7(7) and -15.2(8) kcal mol-1 with ΔS = -42(2) and -35(3) e.u:; for Ar = Ph, ΔH = -14.8(8) and -13.3(6) kcal mol-1 with ΔS = -31(2) and -39(2) e.u.; for Ar = 3,5-C6H3Me2, ΔH = -10.8(6) and -12.7(5) with ΔS = -19(2) and -36(4) e.u., in each case for M = Zr and Hf, respectively. Dynamic NMR analyses reveal that the activation barriers for methide abstraction from the neutral metallocene dialkyls are small and relatively insensitive to the borane identity (AH = 2-6 kcal mol-1) while ion-pair separation/recombination processes are greatly facilitated by polar solvents. Ethylene polymerization activities for eight (Me2Cp)2MCH3+CH3B(C6F5)2Ar- complexes measured in toluene solution (25°C, 1 atm) follow a trend in metal (Zr > Hf)as well as a substantial trend in triarylborane (Ar = C6F5 > 3,5-C6H3F2 > Ph ~3,5-C6H3-Me2). Polymerization activities correlate roughly with MCH3+ 13C NMR chemical shifts and enthalpies of methide abstraction.
Transition metal compound, olefin polymerization catalyst comprising the compound, and process for production of olefin polymer
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, (2008/06/13)
A polyolefin of a high molecular weight is produced by using a catalyst comprising a transition metal compound represented by General Formula (1):
