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《Angewandte Chemie (International ed. in English)》2017,56(38):11645-11648
Diboration of unsaturated organic compounds is an extremely useful reaction in synthetic chemistry. Herein, we report the first diboration of a nitrile by an electron‐rich diborane, mediated by an electrophilic borane. The reaction is metal‐free, and all of the reagents are readily available. 相似文献
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Dr. Longfei Li Mengxian Dong Prof. Hua-Jie Zhu Prof. Bin Peng Dr. Yaoming Xie Prof. Henry F. Schaefer III 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(68):15628-15633
This mechanistic study demonstrates that an unusual η1-coordinated alkyne complex is critical for the 1-pentyne 1,1-diboration reaction. The comparative studies suggest the “pull–push” antagonistic effect arising from Lewis acidity and steric congestion as the reason for the existence of η1-coordinated alkyne complexes. Analogous η1-coordinated alkene complexes are also predicted and seem to be promising for their application to the important olefin polymerization reaction. 相似文献
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Naohisa Nakagawa Prof. Dr. Takuji Hatakeyama Prof. Dr. Masaharu Nakamura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4257-4261
An iron‐catalyzed diboration reaction of alkynes with bis(pinacolato)diboron (B2pin2) and external borating agents (MeOB(OR)2) affords diverse symmetrical or unsymmetrical cis‐1,2‐diborylalkenes. The simple protocol for the diboration reaction can be extended to the iron‐catalyzed carboboration of alkynes with primary and, unprecedentedly, secondary alkyl halides, affording various tetrasubstituted monoborylalkenes in a highly stereoselective manner. DFT calculations indicate that a boryliron intermediate adds across the triple bond of an alkyne to afford an alkenyliron intermediate, which can react with the external trapping agents, borates and alkyl halides. In situ trapping experiments support the intermediacy of the alkenyl iron species using radical probe stubstrates. 相似文献
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Penno D Lillo V Koshevoy IO Sanaú M Ubeda MA Lahuerta P Fernández E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(34):10648-10655
Novel Pd(2) (6+) compounds have been synthesized in high yield. These compounds and their Pd(2) (4+) counterparts as synthetic precursors mediate the diboration of vinylarenes and aliphatic 1-alkenes, and under mild and basic reaction conditions they produce a variety of 1,2-diboronate esters with excellent conversions and chemoselectivities. The presence of bis(catecholato)diboron (B(2)cat(2)) favours the reduction of Pd(III) to Pd(II), while the catalytic precursor of Pd(II) is transformed into Pd(0)-nanoparticles. An "in situ" catalytic tandem reaction has been designed to transform the diboronate intermediates into the monoarylated product, which after oxidative workup, provides the carbohydroxylated adduct. Eventually, the same catalyst performs both sequences with total conversion from the alkene. 相似文献
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Andrea Deissenberger Eileen Welz Regina Drescher Ivo Krummenacher Rian D. Dewhurst Bernd Engels Holger Braunschweig 《Angewandte Chemie (International ed. in English)》2019,58(6):1842-1846
A new structural class of boron‐based diradicals is prepared by Lewis base addition to and reduction of singly cyclic (alkyl)(amino)carbene (CAAC) stabilised diborylalkenes. The diradicals feature a perpendicular olefinic bridge preventing delocalization between the B(CAAC) π systems, making the coupling between the spin centres very weak. DFT calculations indicate that the compounds are ground‐state (open‐shell) singlets, with triplet states negligibly higher in energy, thus making the triplet states easily populated thermally. 相似文献
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An Alkyne Diboration/6π‐Electrocyclization Strategy for the Synthesis of Pyridine Boronic Acid Derivatives
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Helena Mora‐Radó Dr. Laurent Bialy Dr. Werngard Czechtizky Dr. María Méndez Prof. Joseph P. A. Harrity 《Angewandte Chemie (International ed. in English)》2016,55(19):5834-5836
A new and efficient synthesis of pyridine‐based heteroaromatic boronic acid derivatives is reported through a novel diboration/6π‐electrocyclization strategy. This method delivers a range of functionalized heterocycles from readily available starting materials. 相似文献
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Prof. Dr. Keiichi Hirano Kensuke Morimoto Shota Fujioka Prof. Dr. Kazunori Miyamoto Dr. Atsuya Muranaka Prof. Dr. Masanobu Uchiyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21632-21637
1-Boraphenalenes, a class of boron-doped polyaromatic hydrocarbons, were synthesized by nucleophilic diboration reaction of alkynes. Activation of diboron reagents with a highly basic sp2-carbanion results in very fast successive C−B bond formations to construct the boracycle. This methodology is characterized by high chemoselectivity, affording a wide variety of 1-boraphenarenes with diverse polar substituents. The endocyclic boron can be arylated conveniently in one pot, and the peripheral boron is available for various chemical transformations. Highly diastereoselective diboration gives pseudo-enantio-enriched boraphenarene, which emits circularly polarized fluorescence (CPL). 相似文献
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Dr. David Pierrot Prof. Dr. Ilan Marek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20614-20618
The preparation of acyclic molecules featuring congested stereocenters in a 1,4-relationship in only three catalytic steps from commercially available building blocks is reported. This approach involves a diastereoselective diboration of alkenyl cyclopropyl methanol derivatives followed by a regioselective exergonic ring fragmentation. The starting materials can be prepared enantiomerically enriched and all substituents can be interconverted, therefore, this strategy allows a large variety of diversely functionalized allylboronic esters possessing distant tetrasubstituted stereocenters with high diastereoselectivity. 相似文献