97-21-2Relevant articles and documents
Synthesis and structures of new 1,3,6,2-dioxazaborocanes containing substituents in the ocane fragment
Lermontova,Huang,Karlov,Zabalov,Churakov,Neumueller,Zaitseva
experimental part, p. 1920 - 1930 (2009/12/23)
New 1,3,6,2-dioxazaborocanes R1N(CHR3CR 4R2O)(CHR6CHR5O)BX (1-11, X = Ph, 4-MeC6H4, Me; R1 = Me, PhCH2; R 2, R3, R4, R5, R6 = H, Ph) were synthesized by the reactions of aryl- or methylboronic acids with dialkanolamines. The treatment of (Me2NCH2CH 2O)3B (15) with MeN(CH2CH2OH) (CH2CPh2OH) afforded 2-[2-(dime-thylamino)ethoxy]-1,3,6,2- dioxazaborocane (12). 2-Fluoro-1,3,6,2-dioxazaborocanes R1N(CHR 3CHR2O)(CH2CH2O)BF (13: R 1 = PhCH2, R2 = R3 = H; 14: R 1 = Me, R2 = R3 = Ph, threo) were synthesized by the reaction of bis(trimethylsilyl) ethers of the corresponding dialkanolamines with BF3?Et2O. The new borocanes can be used for the synthesis of the corre-sponding germanium derivatives PhCH 2N(CH2CH2O)2GeX2 (16, X = OEt; 17, X = Cl), as exemplified by the reaction of compound 6. The structures of erythro-MeN(CH2CH2O)(CHPhCHPhO)BPh (3), threo-MeN(CH2CH2O)(CHPhCHPhO)BPh (4), erythro-MeN(CH 2CH2O)(CHPhCHPhO)B(4-MeC6H4) (8), and PhCH2N(CH2CH2O)2BF (13) were established by X-ray diffraction. The coordination polyhedra of the boron atoms in these complexes can be described as distorted tetrahedra. The boron-nitrogen distances (1.705(7)-1.723(3) A) provide unambiguous evidence for the presence of the B-N transannular interaction in these compounds. The structures of the resulting borocanes containing phenyl substituents at the carbon atoms of the ocane skeleton were studied by NMR spectroscopy and quantum chemical density functional theory calculations.
A nuclear magnetic resonance study of hydrogen bonding in tris(2-N-methylaminoethyl) borate and similar compounds
Meek, Devon W.,Springer Jr., Charles S.
, p. 445 - 450 (2007/10/05)
Tris(2-aminoethyl) borate, B(OCH2CH2NH2)3, and the analogous N-methylamino and N,N-dimethylamino compounds have been prepared by the transesterification of methyl borate with the appropriate 2-aminoethanol. The nuclear magnetic resonance spectra show that extensive association of the terminal amino groups occurs in pure tris(N-methylaminoethyl) borate and that this association can be broken apart by heating to 160° or by dissolution in polar organic solvents such as triethylamine or acetonitrile. In order to determine whether the association results from hydrogen bonding or internal B-N coordination, several model systems have been investigated. The spectra of NH2C2H5·BF3, piperidine·BF3, and (C6H5)2BO-CH2CH2NH 2 in acetonitrile contain very complicated NCH2 peaks and broad NH peaks which appear at low applied magnetic field (τ 5.26-5.56). The broadening of the NH peak in the boron-nitrogen adducts is attributed to the effect of the N14 quadrupole, whereas the complex splitting of the NCH2 multiplet is attributed to coupling with B11 in the dative bond with nitrogen and possibly with the nitrogen protons. The spectra of B(OCH2CH2NH2)3 and B(OCH2CH2NHCH3)3, on the other hand, show sharp NH peaks at somewhat higher applied magnetic fields (τ 7.84, 6.78) and contain two sharp triplets attributed to the two sets of methylene protons in the -O-CH2-CH2-N2 6.26-6.55; τNCH2 7.23-7.57). The N-H peak of B(OCH2CH2NHCH3)3 appears as a sharp singlet in acetonitrile solutions owing to rapid exchange of the amine proton. Evidence is presented that the exchange is catalyzed by a trace (2CH2NHCH3)3.
