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.
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.
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.
Santucci,Triboulet
, p. 392,395 (1969)
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.
Synthesis of Boroxine and Dioxaborole Covalent Organic Frameworks via Transesterification and Metathesis of Pinacol Boronates
Hamzehpoor, Ehsan,Jonderian, Antranik,McCalla, Eric,Perepichka, Dmitrii F.
supporting information, p. 13274 - 13280 (2021/09/07)
Boroxine and dioxaborole are the first and some of the most studied synthons of covalent organic frameworks (COFs). Despite their wide application in the design of functional COFs over the last 15 years, their synthesis still relies on the original Yaghi's condensation of boronic acids (with itself or with polyfunctional catechols), some of which are difficult to prepare, poorly soluble, or unstable in the presence of water. Here, we propose a new synthetic approach to boroxine COFs (on the basis of the transesterification of pinacol aryl boronates (aryl-Bpins) with methyl boronic acid (MBA) and dioxaborole COFs (through the metathesis of pinacol boronates with MBA-protected catechols). The aryl-Bpin and MBA-protected catechols are easy to purify, highly soluble, and bench-stable. Furthermore, the kinetic analysis of the two model reactions reveals high reversibility (Keq ～1) and facile control over the equilibrium. Unlike the conventional condensation, which forms water as a byproduct, the byproduct of the metathesis (MBA pinacolate) allows for easy kinetic measurements of the COF formation by conventional 1H NMR. We show the generality of this approach by the synthesis of seven known boroxine/dioxaborole COFs whose crystallinity is better or equal to those reported by conventional condensation. We also apply metathesis polymerization to obtain two new COFs, Py4THB and B2HHTP, whose synthesis was previously precluded by the insolubility and hydrolytic instability, respectively, of the boronic acid precursors.
