5523-19-3Relevant academic research and scientific papers
Diethyl(di-tert-butylphosphino)borane and related compounds: The first stable monomeric tetraalkyl phosphinoborane
Groshens, Thomas J.,Higa, Kelvin T.,Nissan, Robin,Butcher, Raymond J.,Freyer, Alan J.
, p. 2904 - 2910 (2008/10/08)
Four new phosphinoborane compounds were prepared and characterized by 1H, 13C, 31P, and 11B NMR spectroscopy and elemental analysis. Monomeric Et2BP(t-Bu)2 was isolated as a volatile yellow liquid and [Me2BP(t-Bu)2]2 as a colorless solid using salt elimination reactions. The colorless dimeric solids [Me2BP(SiMe3)2]2 and [Et2BP(SiMe3)2]2 were prepared via trimethylsilyl halide elimination reactions. The dimeric compounds dissociate in benzene or toluene at ambient temperature, and an equilibrium with the monomeric species is established. Variable-temperature 1H NMR spectroscopy showed that ΔH = -93 kJ/mol and ΔS = -285 J/(mol·K) for the dimerization of Me2BP(t-Bu)2 and ΔH = -55 ± 12 kJ/mol and ΔS = -166 ± 42 J/(mol·K) for the dimerization of Me2BP(SiMe3)2. Inverse 2D 1H/13C correlation studies were applied to monomer-dimer solutions and were vital to assignment of 13C resonances. Solid-state 31P NMR confirmed that [Me2BP(t-Bu)2]2 and [Me2BP(SiMe3)2]2 are dimeric solids. The structure of [Me2BP(t-Bu)2]2 was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P1, a = 8.366(3) A?, b = 8.0808(2) A?, c = 9.311(2) A?, α = 74.98(2)°, β = 78.87(2)°, γ = 64.32(2)°, Z = 1, and R = 0.0628.
Organoboranes. 26. 11B NMR investigation of reactions of 2,3-dimethyl-2-butene with monochloroborane complexes. Preparation and hydroboration characteristics of thexylchloroborane reagents
Brown, Herbert C.,Sikorski, James A.
, p. 28 - 37 (2008/10/08)
Under selected conditions, the hydroboration of 2,3-dimethyl-2-butene with 1 equiv of monochloroborane proceeds cleanly to give the monohydroboration product, thexylchloroborane (ThxBHCl). This reaction was examined with several monochloroborane complexes, including BH2C1·THF, BH2Cl·OEt2, and BH2Cl·SMe2. The resulting thexylchloroboranes were fully characterized by IR and 11B NMR spectroscopy. Monomeric ThxBHCl·THF was obtained cleanly from BH2C1middot;THF. Similarly, monomeric ThxBHCl·SMe2 was obtained cleanly from BH2Cl·SMe2. On the other hand, the product resulting from hydroboration of 2,3-dimethyl-2-butene with BH2Cl·OEt2 was demonstrated to be a complex, equilibrating mixture of thexylborane (dimeric), thexylchloroborane, and thexyldichloroborane. The hydroboration properties of each of these reagents were also examined. Hydroboration of terminal alkenes with the ThxBHCl·THF and ThxBHCl/Et2O reagents led to complex mixtures containing trialkylborane, dialkylchloroborane, and alkyldichloroborane species. However, hydroboration of terminal alkenes with ThxBHCl·SMe2 in CH2Cl2 proceeded cleanly to the desired dialkylchloroborane product. Subsequent oxidation produced the desired primary alcohols in nearly quantitative yields with high regioselectivity.
