75-22-9Relevant academic research and scientific papers
Rhodium-Catalyzed B-H Bond Insertion Reactions of Unstabilized Diazo Compounds Generated in Situ from Tosylhydrazones
Pang, Yue,He, Qiao,Li, Zi-Qi,Yang, Ji-Min,Yu, Jin-Han,Zhu, Shou-Fei,Zhou, Qi-Lin
supporting information, p. 10663 - 10668 (2018/09/06)
Although transition-metal-catalyzed B-H bond insertion of carbenes into stable borane adducts has emerged as a promising method for organoborane synthesis, all the diazo compounds used to date as carbene precursors have had an electron-withdrawing group to stabilize them. Herein, we report a protocol for rhodium-catalyzed B-H bond insertion reactions of unstabilized diazo compounds generated in situ from tosylhydrazones. In addition, by using chiral dirhodium catalysts, we also achieved an asymmetric version of the reaction with good to excellent enantioselectivities (up to 98:2 e.r.). This is the first enantioselective heteroatom-hydrogen bond insertion reaction to use unstabilized diazo compounds as carbene precursors. The protocol exhibited good functional group tolerance and could be carried out on a gram scale. It also enabled one-pot transformation of a carbonyl group to a boryl group enantioselectively. The B-H bond insertion products could be easily transformed into chiral alcohols and other widely used organoboron reagents with enantiomeric fidelity.
Method for the production of amine borane complex (by machine translation)
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Paragraph 0039; 0040, (2017/12/05)
The invention belongs to the technical field of material preparation, in particular relates to a method for the production of amine borane complex. This invention adopts the borane amine of the direct reaction of an inert gas stream, by regulating the ratio of the two, the need for further post-processing, to make the final product amine complex and offer. In the reaction process such impurity is introduced into the salt-free, does not use an organic solvent; the use of borohydride such as the reagent to produce the borane, for now the current system, can avoid direct operation of toxic gas borane. The method of the invention is simple in operation, the product has high purity, low cost, and can be continuous large-scale production. At the same time, the method and other way to produce the amine borane complex equipment compatible, production equipment by simple method can be used to adjust the production. (by machine translation)
Amine-boranes bearing borane-incompatible functionalities: Application to selective amine protection and surface functionalization
Veeraraghavan Ramachandran,Kulkarni, Ameya S.,Zhao, Yan,Mei, Jianguo
supporting information, p. 11885 - 11888 (2016/10/09)
The first general open-flask synthesis of amine-boranes with inexpensive and readily available reagents, such as sodium borohydride, sodium bicarbonate, water, and the desired amines is described. Even amines bearing borane-reactive functionalities, such as alkene, alkyne, hydroxyl, thiol, ester, amide, nitrile, and nitro are well tolerated. Some of these novel amine-boranes represent stable molecules containing potentially incompatible electrophilic and nucleophilic centers in proximity. This convenient scalable synthesis provides a novel class of organic ligands for surface functionalization, as demonstrated by the formation of self-assembled layers of thiol- and alkoxysilane-bearing amine-boranes on gold and silica surfaces, respectively.
Electrophilic C-H borylation and related reactions of B-H boron cations
Prokofjevs, Aleksandrs,Jermaks, Janis,Borovika, Alina,Kampf, Jeff W.,Vedejs, Edwin
, p. 6701 - 6711 (2014/01/06)
Catalytic procedures are described for the amine-directed borylation of aliphatic and aromatic tertiary amine-boranes. Sequential double borylation is observed in cases where two or more C-H bonds are available that allow 5-center or 6-center intramolecular borylation. The HNTf2-catalyzed borylation of benzylamine-boranes provides a practical means for the synthesis of ortho-substituted arylboronic acid derivatives, suitable for Suzuki-Miyaura cross-coupling applications.
Mechanisms of the thermal and catalytic redistributions, oligomerizations, and polymerizations of linear diborazanes
Robertson, Alasdair P. M.,Leitao, Erin M.,Jurca, Titel,Haddow, Mairi F.,Helten, Holger,Lloyd-Jones, Guy C.,Manners, Ian
supporting information, p. 12670 - 12683 (2013/09/23)
Linear diborazanes R3N-BH2-NR2-BH 3 (R = alkyl or H) are often implicated as key intermediates in the dehydrocoupling/dehydrogenation of amine-boranes to form oligo- and polyaminoboranes. Here we report detailed studies of the reactivity of three related examples: Me3N-BH2-NMe2-BH3 (1), Me3N-BH2-NHMe-BH3 (2), and MeNH 2-BH2-NHMe-BH3 (3). The mechanisms of the thermal and catalytic redistributions of 1 were investigated in depth using temporal-concentration studies, deuterium labeling, and DFT calculations. The results indicated that, although the products formed under both thermal and catalytic regimes are identical (Me3N·BH3 (8) and [Me2N-BH2]2 (9a)), the mechanisms of their formation differ significantly. The thermal pathway was found to involve the dissociation of the terminal amine to form [H2B(μ-H)(μ-NMe 2)BH2] (5) and NMe3 as intermediates, with the former operating as a catalyst and accelerating the redistribution of 1. Intermediate 5 was then transformed to amine-borane 8 and the cyclic diborazane 9a by two different mechanisms. In contrast, under catalytic conditions (0.3-2 mol % IrH2POCOP (POCOP = κ3-1,3-(OPtBu 2)2C6H3)), 8 was found to inhibit the redistribution of 1 by coordination to the Ir-center. Furthermore, the catalytic pathway involved direct formation of 8 and Me2Ni - BH2 (9b), which spontaneously dimerizes to give 9a, with the absence of 5 and BH3 as intermediates. The mechanisms elucidated for 1 are also likely to be applicable to other diborazanes, for example, 2 and 3, for which detailed mechanistic studies are impaired by complex post-redistribution chemistry. This includes both metal-free and metal-mediated oligomerization of MeNHi - BH2 (10) to form oligoaminoborane [MeNH-BH 2]x (11) or polyaminoborane [MeNH-BH2] n (16) following the initial redistribution reaction.
Catalytic redistribution and polymerization of diborazanes: Unexpected observation of metal-free hydrogen transfer between aminoboranes and amine-boranes
Robertson, Alasdair P. M.,Leitao, Erin M.,Manners, Ian
, p. 19322 - 19325 (2012/01/13)
Ir-catalyzed (20 °C) or thermal (70 °C) dehydrocoupling of the linear diborazane MeNH2-BH2-NHMe-BH3 led to the formation of poly- or oligoaminoboranes [MeNH-BH2]x (x = 3 to >1000) via an initial redistribution process that forms MeNH 2?BH3 and also transient MeNH=BH2, which exists in the predominantly metal-bound and free forms, respectively. Studies of analogous chemistry led to the discovery of metal-free hydrogenation of the B=N bond in the "model" aminoborane iPr2N=BH2 to give iPr2NH?BH3 upon treatment with the diborazane Me3N-BH2-NHMe-BH3 or amine-boranes RR′NH?BH3 (R, R′ = H or Me).
Structures and aggregation of the methylamine-borane molecules, Me nH3-nN BH3 (n = 1-3), studied by X-ray diffraction, gas-phase electron diffraction, and quantum chemical calculations
Aldridge, Simon,Downs, Anthony J.,Tang, Christina Y.,Parsons, Simon,Clarke, Michael C.,et al.
, p. 2231 - 2243 (2009/07/30)
The structures of the molecules methylamine-borane, MeH2 ? BH3, and dimethylamine-borane, Me2HN? BH3, have been investigated by gas-phase electron diffraction (GED) and quantum chemical calculations. The crystal structures have also been determined for methylamine-, dimethylamine-, and trimethylamine-borane, MenH 3-nN ? BH3 (n = 1-3); these are noteworthy for what they reveal about the intermolecular interactions and, particularly, the N-H...H-B dihydrogen bonding in the cases where n = 1 or 2. Hence, structures are now known for all the members of the ammonia- and amine-borane series MenH3-nN?BH3 (n = 0-3) in both the gas and solid phases. The structur al variations and energetics of formation of the gaseous adducts are discussed in relation to the basicity of the Me nH3-nN fragment. The relative importance of secondary interactions in the solid adducts with n = 0-3 has been assessed by the semi-classical density sums (SCDS-PIXEL) approach.
Real-time evaluation of aluminum borohydride trimethylamine for aluminum chemical vapor deposition
Kang, Sang-Woo,Park, Young-Jae,Kim, Yong-Sung,Shin, Yong-Hyeon,Yun, Ju-Young
, p. H333-H339 (2009/05/30)
The chemical species in gas phase and on the surface of aluminum borohydride trimethylamine (ABHTMA) for aluminum chemical vapor deposition as a function of the hot-wall temperature and the chamber pressure were studied using two kinds of Fourier transfor
Molecular structure and dynamics in the low temperature (orthorhombic) phase of NH3BH3
Cho, Herman,Shaw, Wendy J.,Parvanov, Vencislav,Schenter, Gregory K.,Karkamkar, Abhijeet,Hess, Nancy J.,Mundy, Chris,Kathmann, Shawn,Sears, Jesse,Lipton, Andrew S.,Ellis, Paul D.,Thomas Autrey
, p. 4277 - 4283 (2009/02/01)
Variable temperature 2H NMR experiments on the orthorhombic phase of selectively deuterated NH3BH3 spanning the static to fast exchange limits of the borane and amine motions are reported. New values of the electric field gradient (EFG) tensor parameters have been obtained from the static 2H spectra of Vzz = 1.652 (±0.082) × 1021 V/m2 and η = 0.00 ± 0.05 for the borane hydrogens and Vzz = 2.883 (±0.144) × 10 21 V/m2 and η = 0.00 ± 0.05 for the amine hydrogens. The molecular symmetry inferred from the observation of equal EFG tensors for the three borane hydrogens and likewise for the three amine hydrogens is in sharp contrast with the Cs symmetry derived from diffraction studies. The origin of the apparent discrepancy has been investigated using molecular dynamics methods in combination with electronic structure calculations of NMR parameters, bond lengths, and bond angles. The computation of parameters from a statistical ensemble rather than from a single set of atomic Cartesian coordinates gives values that are in close quantitative agreement with the 2H NMR electric field gradient tensor measurements and are more consistent with the molecular symmetry revealed by the NMR spectra.
Heterogeneous or homogeneous catalysis? Mechanistic studies of the rhodium-catalyzed dehydrocoupling of amine-borane and phosphine-borane adducts
Jaska, Cory A.,Manners, Ian
, p. 9776 - 9785 (2007/10/03)
In depth, comparative studies on the catalytic dehydrocoupling of the amine-borane adduct Me2NH-BH3 (to form [Me 2N-BH2]2) and the phosphine-borane adduct Ph2PH·BH3 (to form Ph2PH-BH 2-PPh2-BH3) with a variety of Rh (pre)catalysts such as [{Rh(1,5-cod)(μ-Cl)}2], Rh/Al2O3, Rhcolloid/[Oc4N]Cl, and [Rh(1,5-cOd)2]OTf have been performed in order to determine whether the dehydrocoupling proceeds by a homogeneous or heterogeneous mechanism. The results obtained suggest that the catalytic dehydrocoupling of Me2NH·BH3 is heterogeneous in nature involving Rh(0) colloids, while that of Ph 2PH·BH3 proceeds by a homogeneous mechanism even when starting with Rh(0) precursors such as Rh/Al2O3. The catalytic dehydrocoupling reactions are thought to proceed by different mechanisms due to a combination of factors such as (i) the greater reducing strength of amine-borane adducts, (ii) the increased ease of dissociation of phosphine-borane adducts, and (iii) phosphine ligation and/or poisoning of active catalytic sites on metal colloids.
