3262-89-3Relevant articles and documents
Synthesis of B,O,N-Doped Adamantanes and Diamantanes by Condensation of Oximes with Boronic Acids
Golovanov, Ivan S.,Sukhorukov, Alexey Yu.,Nelyubina, Yulia V.,Khomutova, Yulia A.,Ioffe, Sema L.,Tartakovsky, Vladimir A.
, p. 6728 - 6736 (2015)
Condensation of oximes with boronic acids RB(OH)2 or B(OH)3 affords remarkably stable 2,4,10-trioxa-1,5,7-triaza-3-boroadamantanes via an unprecedented multicomponent process. The mechanism involves the reversible generation of unstable oxime cyclotrimers, which are readily intercepted by boronic acids.
Structural Induction via Solvent Variation in Assemblies of Triphenylboroxine and Piperazine - Potential Application as Self-Assembly Molecular Sponge
Torres-Huerta, Aaron,Velásquez-Hernández, Miriam De Jesús,Martínez-Otero, Diego,H?pfl, Herbert,Jancik, Vojtech
, p. 2438 - 2452 (2017)
This study examined the direct effect of solvent on the chemical composition and structure of supramolecular assemblies formed from triphenylboroxine ((PhBO)3) and piperazine (ppz) through N→B bonds. Oxygen-containing solvents with a molecular size smaller than 4.1 ? produce 1D polymeric structures (1:1 boroxine/piperazine) of compositions {(PhBO)3(ppz)}n·nTHF (1a·THF) and {(PhBO)3(ppz)}n·nAcetone (1a·Acetone), in which the boroxine B3O3 rings are linked through N→B bonded piperazine molecules in a cis-conformation. In both cases, a pseudocavity is generated between two polymer chains, which is occupied by a solvent molecule interacting through bifurcated N-H···O···H-N hydrogen bonds with one of the chains. In contrast, oxygen-based solvents with a size larger than 6.3 ? give rise to discrete 2:1 assemblies, {(PhBO)3}2(ppz)·2Ethyl acetate (2·AcOEt) and {(PhBO)3}2(ppz)·2Pentanone (2·Pentanone), with the piperazine molecule bridging two B3O3 rings and interacting with two solvent molecules via N-H···O hydrogen bonds. In chloroform or dichloromethane 2:3 adducts, {(PhBO)3}2(ppz)3·4CHCl3 (3·CHCl3) and {(PhBO)3}2(ppz)3·2.09CH2Cl2 (3·CH2Cl2), were obtained, with N-H···N interactions formed between the piperazine molecules directing the crystal lattice. Finally, unlike with THF and acetone, the presence of two coordination sites in dioxane gives rise to a 1D polymeric 1:1 clathrate-type assembly with trans-conformation, {(PhBO)3(ppz)}n·3.5nDioxane (1b·Dioxane). In accordance with the structural characterization, the thermogravimetric analysis of compounds 1-2 evidenced relatively high decomposition (solvent elimination) temperatures for the inclusion complexes derived from oxygen-containing solvents (Tpeak = 76.4 to 145.4 °C). On the contrary, solvates based on halogenated solvents (3·CHCl3 and 3·CH2Cl2) or 1,4-dioxane started to decompose already at room temperature. In view of potential applications for the storage and structural characterization of volatile or highly reactive reagents, a final inclusion experiment was carried out with racemic 1,2-epoxybutane. As expected, the resulting N→B bonded inclusion complex exhibited a 1:1 cis-polymeric structure, in which the guest molecules were bonded by bifurcated Npip-H···Oepoxy···H-Npip hydrogen bonds.
Ring expansion reactions of pentaphenylborole with dipolar molecules as a route to seven-membered boron heterocycles
Huang, Kexuan,Martin, Caleb D.
, p. 1869 - 1875 (2015)
Reactions of pentaphenylborole with isocyanates, benzophenone, and benzaldehyde produced new seven-membered heterocycles in high yields. For 1-adamantyl isocyanate, a BNC5 heterocycle was obtained from the insertion of the C-N moiety into the five-membered borole, whereas for 4-methoxyphenyl isocyanate, a BOC5 heterocycle was generated from the insertion of the C-O unit. These reactions are believed to occur via a mechanism wherein coordination of the nucleophile to the borole (1-adamantyl, N-coordination or O-coordination for 4-methoxyphenyl) is followed by ring expansion to afford the observed seven-membered heterocycles. The selectivity to form B-O- or B-N-containing heterocycles is based on the polarization of the isocyanate implying tunable reactivity for the system. Having observed that isocyanates react as 1,2-dipoles with pentaphenylborole, we examined benzophenone and benzaldehyde, which both reacted to insert C-O units into the ring. This represents a new efficient method for preparing rare seven-membered boracycles.
Solubility of Phenylboronic Acid and its Cyclic Esters in Organic Solvents
Leszczyński, Pawe?,Hofman, Tadeusz,Sporzyński, Andrzej
, p. 814 - 824 (2020)
The solubilities of phenylboronic acid, its pinacol ester and azaester in organic solvents (chloroform, 3-pentanone, acetone, dipropyl ether and methylcyclohexane) have been determined experimentally by a dynamic method, in which the disappearance of turbidity was determined by measuring of light intensity using a luminance probe. Phenylboronic acid has high solubility in ether and ketones, moderate in chloroform and very low in hydrocarbon. Pinacol ester and azaester show better solubility than the parent acid in all tested solvents. For pinacol ester differences between particular solvents are small, while for azaester the differences are significant. For both esters the highest solubility is observed in chloroform and the lowest in the hydrocarbon. The results have been correlated by the Wilson, NRTL and Redlich–Kister equations. For the phenylboronic acid better correlation of the data is obtained by polynomials in comparison with the above equations. It is connected with additional acid-anhydride equilibrium in the system. The influence of polarity of the solvents on the solubility is discussed.
Reversible formation of organyl(oxo)boranes (RBO) (R = C6H 5 or CH3) from boroxins ((RBO)3): A matrix isolation study
Bettinger, Holger F.
, p. 6263 - 6267 (2007)
Flash vacuum pyrolysis of triphenyl- and trimethylboroxin and subsequent trapping of the gas phase products in a large excess of argon at T 3BO, 1:1 dimer complex of CH3BO, (CH3BO)2, and (CH3BO)3, depends strongly on the trapping temperature and matrix host gas (Ar vs Xe) with the boroxin dominating at 30 K (Ar) or 55 K (Xe). An ab initio investigation (second-order Moller - Plesset perturbation theory) of the potential energy surface for trimerization of CH3BO is in agreement with the experimental observations.
Can triorganoboroxins exist in a "monomeric" R-B=O form? MNDO calculations and ebulliometric molecular weight determination
Sporzynski, Andrzej,Szatylowicz, Halina
, p. 31 - 34 (1994)
MNDO calculations were made for triethylboroxin (EtBO)3 and triphenylboroxin (PhBO)3 using both X-ray determined and optimized geometry of these molecules.The results were compared with hypothetical "monomeric" molecules R-B-O.Calculated energies of trimerization are about -200 kJ mol-1 for both compounds and confirm the much higher stability of the "trimer".Ebulliometric determination of molecular weight of triphenylboroxin in 2-pentanone confirms its trimeric character. Key words: Boroxin; MNDO calculations
Bimetallic zirconium heterocycles supported by boron-oxygen ligands
Balkwill, Jessica E.,Cole, Sarah C.,Coles, Martyn P.,Hitchcock, Peter B.
, p. 3548 - 3552 (2002)
Reaction between bis(cyclopentadienyl)dimethylzirconium, ZrCp2(CH3)2, and phenylboronic anhydride, (PhBO)3, resulted in the formation of the heterocyclic dimer [ZrCp2{μ-O2BPh}]2 (1); no reaction was observed with the mesityl derivative, (mesBO)3. Compound 1 was also synthesized from the protonolysis reaction between ZrCp2-(CH3)2 and in situ generated phenylboronic acid, PhB(OH)2. This approach was extended to afford the analogous complexes [ZrCp2{μ-O2BAr}]2 (2, Ar = mes; 3, Ar = C6F5) from the corresponding isolable arylboronic acids, ArB(OH)2. The molecular structures of 1-3, determined by X-ray diffraction techniques, revealed a common, dimeric motif consisting of a central "Zr2B2O4" metallacycle. Variations in the bond parameters within the heterocycle are attributed to the differing steric and electronic properties of the aryl substituents at boron.
Dehydration of phenylboronic acid to boroxine catalyzed by Aun nanoclusters with atom packing core-shell structure
Huang, Ping,Jiang, Zhi,Chen, Guoxiang,Zhu, Yan,Sun, Yuhan
, p. 5088 - 5092 (2013)
Atomically precise Aun nanoclusters (n = number of gold atom in cluster) ideally composed of an exact number of gold atoms have unique core-shell structure and non-metallic electronic properties. The extremely small size of Au25 and Au38 nanoclusters induces a large energy gap in their electronic structures, which gives rise to unprecedented catalytic activity in some chemical reactions. Here we report dehydration of phenylboronic acid to boroxine with small Au25 and Au38 nanocluster catalysts, respectively. Especially, Au25 nanocluster is arranged with Au13 icosahedral core capped by twelve gold atoms as an exterior shell. Au38 nanocluster is a face-fused biicosahedral Au 23 core encapsulated by a shell comprised of fifteen gold atoms. Au38 nanoclusters exhibit higher activity than Au25 nanoclusters. This study is an attempt to provide a powerful tool for the catalyst design and to gain a further insight into the correlation of structural properties with catalytic properties. Copyright
Increments for 1H and 13C NMR chemical shifts in areneboronic acids
Bruns, Stefan,Sinnwell, Volker,Voss, Juergen
, p. 269 - 272 (2003)
A series of areneboronic acids were studied by NMR spectroscopy. Increments for the 1H and 13C chemical shifts caused by the boronic acid substituent B(OH)2 in areneboronic acids were determined. Copyright
Reductive Alkylation of Quinolines to N-Alkyl Tetrahydroquinolines Catalyzed by Arylboronic Acid
Adhikari, Priyanka,Bhattacharyya, Dipanjan,Nandi, Sekhar,Kancharla, Pavan K.,Das, Animesh
supporting information, p. 2437 - 2442 (2021/04/05)
A boronic acid catalyzed one-pot tandem reduction of quinolines to tetrahydroquinolines followed by reductive alkylation by the aldehyde has been demonstrated. This step-economcial synthesis of N-alkyl tetrahydroquinolines has been achieved directly from readily available quinolines, aldehydes, and Hantzsch ester under mild reaction conditions. The mechanistic study demonstrates the unique behavior of organoboron catalysts as both Lewis acids and hydrogen-bond donors.
