2622-89-1

Imidazo[1,5-a]pyridin-1-ylalkyl alcohols were reacted with diphenylborinic acid to give boron complexes in which nitrogen and oxygen atoms were coordinated to a boron atom. The use of imidazo[1,5-a]pyridin-1-ylalkyl alcohol with two 2-pyridyl groups also

The size, shape, and number of nucleoli in a cell's nucleus might help to distinguish a malignant from a benign tumor. Cellular biology and histopathology often require better visualization to understand nucleoli-related processes, thus organelle-specific fluorescent markers are needed. Here, we report the design, synthesis, and fully chemo-photophysical characterization of fluorescent boron Schiff bases (BOSCHIBAs), derived from α-amino acids (i.e., phenylalanine, tyrosine and tryptophan), with nucleoli- and cytoplasm-specific staining in cells. It is the first time that Boron Schiff bases derived from α-amino acids act as notorious dual (nucleoli and cytoplasm) cell-staining fluorescent probes. The boron derivatives not only showed good photostability and acceptable quantum yields (～5%) in solution, but also exhibited low cytotoxicity (>90% cell viability at 0.1 and 1 μg mL-1), which make them good candidates to be used in medical diagnosis. This journal is

Decreased levels of glutamate and changes in several markers of glutamatergic function occur in movement disorders and chronic psychiatric illnesses. Ionotropic glutamate receptors have been implicated in neuronal cell death, and have, therefore, been related to the process of neurodegenerative diseases. Drugs that interact with the glutamatergic system are important tools for the development of better therapies. We examined the effect of a new glutamatergic analog, (+)-(S)-4-(2,2-diphenyl-1,3,2-oxazabolidin-5-oxo)propionic acid, (+)-(S)-Trujillon, on the spontaneous globus pallidus neuronal activity of the anesthetized rat. (+)-(S)-Trujillon excited most pallidal neurons in a dose-dependent manner. Furthermore, blockade of NMDA receptors (NMDARs) inhibited the (+)-(S)-Trujillon-induced excitation, whereas blockade of AMPA/kainate receptors did not. In addition, computational docking studies showed micromolar-range affinities of (+)-(S)-Trujillon for NR2A NMDARs. Our results indicate that (+)-(S)-Trujillon selectively activates NMDARs, an effect that could prove to be a useful tool in the analysis of motor, behavioral, and cognitive disorders, where NMDAR-mediated signaling is altered. Copyright

An attenuated total reflectance Fourier transform infrared (ATR-IR) spectroscopic method has been developed to quantitatively measure, in situ, the surface-facilitated degradation of tetraphenylboron (TPB) in fully aquated clay pastes. Two pathways for degradation of TPB could be studied both independently and simultaneously. Surface-facilitated oxidation of TPB to diphenylboric acid (DPBA) at Lewis acid sites on clay mineral surfaces was investigated on three members of the smectite family of clays. -from Authors

Organic dyes emitting in the second near-infrared (NIR-II, 900–1700 nm) window, with high molar extinction coefficients (MEC) and quantum yields (QY) in aqueous, are essential for in vivo bioimaging and biosensing. In this work, we developed a dibodipy-based aggregation-induced emission (AIE) fluorescent probe, THPP, to meet this aim. THPP exhibits a high MEC and has intensified absorption and emission in J-aggregated state, which significantly enhance the fluorescence intensity (≈55 folds) and extend the maximal absorption/emission wavelengths to 970/1010 nm in NIR-II region. Based on the bright THPP, imaging with a high frame rate (34 frames per second) at a deep “valid penetration depth” up to 6 mm can be achieved. This enabled simultaneous and dynamic imaging of vasculatures and deep tissues. Besides, we succeeded in monitoring the respiratory rate of acute-lung-injury mice and tracing the collateral circulation process with a high frame rate.

We observed an unusual formation of four-coordinate boron(III) complexes from the reaction of 1-(2-pyridinyl)-5-pyrazolone derivatives with arylboronic acids in the basic media. The exact mechanism is not clear; however, the use of unprotected boronic acid and the presence of a bidentate ligand appeared to be the key structural requirements for the transformation. The results suggest that base-promoted disproportionation of arylboronic acid with the assistance of the [N,O]-bidentate ligation of 1-(2-pyridinyl)-5-pyrazolone should take place and facilitate the formation of pyrazole di-arylborinate. Experiments to obtain a deeper understanding of its mechanism are currently underway.

The palladium-catalyzed synthesis of diarylborinic acid derivatives by intermolecular cross-coupling between aryl iodides and (amino)dihydrideborane is reported. The key to success of the reaction is the use of a less bulky diethylaminoborane reagent, which facilitates the second B-arylation.

Tetracoordinate organoborate compounds, such as compounds harboring a tetraarylborate anion or a triarylalkylborate anion, are shown to exhibit a selective bacteriostatic and bactericidal effect against pathogenic Neisseria species such as N. meningitidis

The development of catalyst-controlled, site-selective C(sp 3)-H functionalization reactions is currently a major challenge in organic synthesis. In this paper, a novel bond-weakening catalyst that recognizes the hydroxy group of alcohols through formation of a borate is described. An electron-deficient borinic acid-ethanolamine complex enhances the chemical yield of the α-C-H alkylation of alcohols when used in conjunction with a photoredox catalyst and a hydrogen atom transfer catalyst under irradiation with visible light. This ternary hybrid catalyst system can, for example, be applied to functional-group-enriched-peptides.

Certain borenium cations supported by carbenes can function as hydrogenation catalysts for imines. While many carbenes have been explored, variation of the other groups on boron has been less common. We have investigated several carbene-borane adducts in an attempt to understand the ability of a bis-amino cyclopropenylidene (BAC) carbene dicyclohexylborane adduct to hydrogenate relatively sterically unhindered benzyl imines. As an additional variant, a BAC carbene adduct of diphenylborane was prepared. A convenient preparation of diphenylboron fluoride via a potassium fluoroborinate salt was employed in this chemistry. Reaction of diphenylboron fluoride with a BAC carbene afforded a modest yield of a carbene-fluoroborane adduct. Reaction between the fluoroborinate salt and a lithium tetrafluoroborate adduct of the carbene provided the adduct in much improved yield and cleanliness, and the product was structurally characterized. The fluoroborate could be converted to a boron hydride through fluoride-hydride exchange with dimethylchlorosilane. The boron hydride adduct was also structurally characterized. Unlike the BAC carbene dicyclohexylborane adduct, the BAC carbene diphenylborane adduct showed essentially no activity in hydrogenation of imines or enamines.

A synthesis of borinic acids and borinates was optimized using amine-borane complexes as a water and air insensitive borylating agent. The reaction operates under convenient conditions using a non-cryogenic temperature and with no flash chromatography, and it gives no boron impurities. The reaction proceeds through a tandem dehydrogenation-double addition mechanism.

Steric bulk prevents the formation of strong bonds between Lewis acids and bases in frustrated Lewis pairs (FLPs), where latent reactivity makes these reagents transformative in small molecule activations and metal-free catalysis. However, their use as a platform for developing materials chemistry is unexplored. Here we report a fully macromolecular FLP, built from linear copolymers that containing either a sterically encumbered Lewis base or Lewis acid as a pendant functional group. The target functional copolymers were prepared by a controlled radical copolymerization of styrene with designer boron or phosphorus containing monomers. Mixtures of the B- and P-functionalized polystyrenes do not react, with the steric bulk of the functional monomers preventing the favorable Lewis acid base interaction. Addition of a small molecule (diethyl azodicarboxylate) promotes rapid network formation, cross-linking the reactive polymer chains. The resulting gel is dynamic, can self-heal, is heat responsive, and can be reshaped by postgelation processing.

Lower Lewis acidity boranes demonstrate greater tolerance to combinations of water/strong Br?nsted bases than B(C6F5)3, this enables Si?H bond activation by a frustrated Lewis pair (FLP) mechanism to proceed in the presence of H2O/alkylamines. Specifically, BPh3has improved water tolerance in the presence of alkylamines as the Br?nsted acidic adduct H2O–BPh3does not undergo irreversible deprotonation with aliphatic amines in contrast to H2O–B(C6F5)3. Therefore BPh3is a catalyst for the reductive amination of aldehydes and ketones with alkylamines using silanes as reductants. A range of amines inaccessible using B(C6F5)3as catalyst, were accessible by reductive amination catalysed by BPh3via an operationally simple methodology requiring no purification of BPh3or reagents/solvent. BPh3has a complementary reductive amination scope to B(C6F5)3with the former not an effective catalyst for the reductive amination of arylamines, while the latter is not an effective catalyst for the reductive amination of alkylamines. This disparity is due to the different pKavalues of the water–borane adducts and the greater susceptibility of BPh3species towards protodeboronation. An understanding of the deactivation processes occurring using B(C6F5)3and BPh3as reductive amination catalysts led to the identification of a third triarylborane, B(3,5-Cl2C6H3)3, that has a broader substrate scope being able to catalyse the reductive amination of both aryl and alkyl amines with carbonyls.

Five coumarin-based polarized ethylenes (enaminoketones, enaminoester and enaminoamide) were prepared using the condensation of the parent β-dicarbonyl compounds with 6-aminocoumarin. Reaction of the polarized ethylenes with an appropriate source of trivalent boron gave corresponding boron β-iminoenolates having either BF2 or BPh2 fragment. The prepared iminoenolates were characterized by means of multinuclear magnetic resonance in solution, single-crystal X-ray diffraction and UV/Vis spectroscopy. A preliminary luminescence study of the iminoenolates as well as their parent enamines was done. The compounds exhibited fluorescence in a solid state as well as in a frozen 2-methyltetrahydrofuran at 77 K. Exploratory tests showed promising AIE/AIEE properties of the tested compounds. On the other hand, no fluorescence in a solution state (with one exception) was observed.

The catalytic synthesis of peptides is a major challenge in the modern organic chemistry hindered by the well-established use of stoichiometric coupling reagents. Herein, we describe for the first time that borinic acid is able to catalyse this reaction under mild conditions with an improved activity compared to our recently developed thiophene-based boronic acid. This catalyst is particularly efficient for peptide bond synthesis affording dipeptides in good yields without detectable racemization.

The present invention relates to a method for preparing borinic acid derivatives and novel borinic acid derivatives. The preparing method of the present invention provides borinic acid derivatives of general formula (2): [in-line-formulae](Ar?2B(OH) ??(2)[/in-line-formulae] wherein Ar is the same as defined in the description and claims, selectively and in a high yield by reacting a compound of general formula (1): [in-line-formulae]Ar-M, ??(1)[/in-line-formulae] wherein Ar and M are the same as defined in the description and claims, with tri-t-butyl borate and then hydrolyzing the reaction product.

In situ formation of aryl Grignard under Barbier condition and diisopropylaminoborane as boron source allows a complete control of the addition onto the boron electrophile. Analytically pure borinic acid derivatives were produced at the gram scale without column chromatography and isolated as borinates adducts, with ethanolamine or 8-hydroxyquinoline, after workup.

2-Aminoethyl diphenylborinate (2-APB) is a known modulator of the IP 3 receptor, the calcium ATPase SERCA, the calcium release-activated calcium channel Orai and TRP channels. More recently, it was shown that 2-APB is an efficient inhibitor of the epithelial calcium channel TRPV6 which is overexpressed in prostate cancer. We have conducted a structure-activity relationship study of 2-APB congeners to understand their inhibitory mode of action on TRPV6. Whereas modifying the aminoethyl moiety did not significantly change TRPV6 inhibition, substitution of the phenyl rings of 2-APB did. Our data show that the diaryl borinate moiety is required for biological activity and that the substitution pattern of the aryl rings can influence TRPV6 versus SOCE inhibition. We have also discovered that 2-APB is hydrolyzed and transesterified within minutes in solution.

(Chemical Equation Presented) In an aqueous solution of acetic acid, PdCl2(PPh3)2 showed high catalytic activity for the hydrophenylation of both terminal and internal alkynes with sodium tetraphenylborate (NaBPh4) under mild conditions, affording phenyl alkenes in moderate to excellent yields.

Quenching of aryl Grignard reagents with 2-isopropoxy-4,4,5,5-tetramethyl- 1,3,2-dioxaborolane (isopropyl pinacol borate) under noncryogenic conditions can lead to mixtures of the corresponding boronic ester along with, generally undesired, borinic acid derivatives. We have found that in certain cases gentle heating of the crude reaction mixtures leads to complete equilibration to give the borinic esters as the sole product which can then be isolated in high yield. This novel equilibration can reduce the need for use of cryogenic conditions or large excesses of reagents to obtain selectivity during boronic ester syntheses.

A reaction of 3-acetyl-4-amino-5,5,5-trifluoropent-3-en-2-one diphenylboron chelate and ammonia or primary amines affords 4-amino-or 4-alkylamino-3- trifluoroacetimidoylpent-3-en-2-ones, new reagents which can be used for the synthesis of pyrimidines with trifluoromethyl group.

Compounds containing B-N bonds have shown interesting biological activity. One class of such molecules is the 2,2-diphenyl-1,3,2-oxazaborolidin-5-ones (3a-j), which contain a B-N bond, have an α-amino acid moiety in the heterocycle, and have an exocyclic

We have synthesized a series of 2-aminoethoxydiphenyl borate (2-APB, 2,2-diphenyl-1,3,2-oxazaborolidine) analogs and tested their ability to inhibit thrombin-induced Ca2+ influx in human platelets. The analogs were either synthesized by adding various substituents to the oxazaborolidine ring (methyl, dimethyl, tert-butyl, phenyl, methyl phenyl, and pyridyl) or increasing the size of the oxazaborolidine ring to seven- and nine-membered rings. NMR analysis of the boron-containing analogs suggests that each of them exist as a ring structure through the formation of an N→B coordinate bond (except for the hexyl analog). The possibility that these boron-containing compounds formed dimers was also considered. All compounds dose-dependently inhibited thrombin-induced Ca2+ influx in human platelets, with the 2,2-diphenyl-1,3,2-oxazaborolidine-5-one derivative having the weakest activity at 100 μM, whereas the (S)-4-benzyl and (R)-4-benzyl derivatives of 2-APB were approximately 10 times more potent than the parent 2-APB. Two nonboron analogs (3-methyl and 3-tert-butyl 2,2-diphenyl-1,3-oxazolidine) were synthesized; they had approximately the same activity as 2-APB, and this implies that the presence of boron was not necessary for inhibitory activity. All of the compounds tested were also able to inhibit thrombininduced calcium release. We concluded that extensive modifications of the oxazaborolidine ring in 2-APB can be made, and Ca2+-blocking activity was maintained. Copyright

A compound of the formula or a pharmaceutically acceptable salt thereof,whereinR1, R2, and R3 are the same or different and are independently hydrogen, lower alkyl, aryl or substituted aryl, lower alkoxy, lower alkoxyalkyl, or cycloalkyl or cycloalkyl alkoxy, where each cycloalkyl group has from 3-7 members, where up to two of the cycloalkyl members are optionally hetero atoms selected from oxygen and nitrogen, and where any member of the alkyl, aryl or cycloalkyl group is optionally substituted with halogen, lower alkyl or lower alkoxy, aryl or substituted aryl, andwhereR3 can be ribose, deoxyribose or phosphorylated derivatives thereof,whereinR1, R2, and R3 are not all hydrogen andwhereinwhen R3 is ribose, deoxyribose or phosphorylated derivatives thereof, one of R1 or R2 is not hydrogen.

An industrial production-scale process currently conducted at Clariant site/Frankfurt, termed Phenyl Boronic Acid Process from here on, was investigated at laboratory-scale using two micromixer/tubular reactor configurations, being equipped with either a glass interdigital (for details see (1) Ehrfeld, W.; Golbig, K.; Hessel, V.; Loewe, H.; Richter, T. Characterization of mixing in micromixers by a test reaction: single mixing units and mixer arrays. Ind. Eng. Chem. Res. 1999, 38, (3), 1075-1082; (2) Hessel, V.; Hardt, S.; Loewe, H.; Schoenfeld, F. Laminar mixing in different interdigital micromixers - Part I: Experimental characterization. AIChE J. 2003, 49, 566-577; (3) Hardt, S.; Schoenfeld, F. Laminar Mixing in Different Interdigital Micromixers - Part 2: Numerical Simulations. AIChE J. 2003, 49, 578-584; (4) Herweck, T.; Hardt, S.; Hessel, V.; Loewe, H.; Hofmann, C.; Weise, F.; Dietrich, T.; Freitag, A. Visualization of Flow Patterns and Chemical Synthesis in Transparent Micromixers. In Topical Conference Proceedings; IMRET 5, 5th International Conference on Microreaction Technology, AIChE Spring National Meeting; Matlosz, M., Ehrfeld, W., Baselt, J. P., Eds.; Springer-Verlag: Berlin, 2001; pp 215-229) or a steel split-recombine mixer (for details see Schoenfeld, F.; Hessel, V.; Hofmann, C. An Optimised Split-and-Recombine Micro Mixer with Uniform 'Chaotic' Mixing. Lab Chip 2004, 4, 65-69). The best yield of the microreactor investigations was 89%, exceeding the performance of the industrially employed stirred-tank process by nearly 25%. Moreover, the total amount of side and consecutive products was decreased from 10-15% to 5-10%. In addition to these yield improvements, the energy expenditure of the microreactor processing was also notably reduced, first of all because of carrying out the reaction at favorable ambient temperature. In contrast, the former batch process had to be carried out at cryogenic temperatures of -35°C. Even at temperatures as high as 50°C, a high selectivity was maintained when using the microreactor. As a further cause for energy savings, the higher purity of the product eliminated the need for distillation; in total therefore, only one heating-cooling cycle with reduced temperature difference was required for the microreactor process in contrast to the three cycles with large temperature differences used in conventional processing. Facing production and process liability issues, a specially made pilot-scale configuration was constructed entirely out of stainless steel components, among them a split-recombine caterpillar mixer having larger internal fluid channels than the interdigital glass mixer. The new configuration allowed one to perform scale-up studies at throughputs as high as 10 L/h.

The catalytic cross-coupling reaction of potassium diaryldifluoroborates with aryl halides proceeds to afford the biphenyls in good yields. These salts on an arylation reagent were readily prepared via a protocol of the Grignard method and transformation to potassium salts. Two aryl groups of these salts were efficiently transferred in the Suzuki-Miyaura reaction.

Two diphenylboron ortho-aminophenolate complexes, [BPh2(OC6H4(CH2NMe2)-2)] (2) and [BPh2(OC6H2(CH2NMe 2)2-2,6-Me-4)] (6), have been prepared in a

Boron chelates obtained from salicylaldehyde and 2'-hydroxyacetophenone azines are colored compounds with potential applications in analytical chemistry. Up to now these complexes have not been studied by X-ray crystallography, although two structures with a six- or a seven-membered chelate ring are possible. This contribution presents the X-ray analysis of 2'-hydroxyacetophenone azine and its corresponding new mono(diphenylboron) chelate with a six-membered boron heterocyclic ring. With these data structural changes of the ligand on chelate formation and structural differences in comparison to salicylaldehyde azomethine boron chelates are discussed.

(3-Hydroxy-2-methyl-1-(p-tolyl)-4-pyridinonato)diphenylboron has been prepared in high yield by the reaction of 3-hydroxy-2-methyl-1-(p-tolyl)-4-pyridinone with diphenylborinic acid.Crystals of the hemi-acetone solvate are triclinic, a = 15.119(2), b = 16.528(1), c = 9.5802(9) Angstroem, α = 98.721(6), β = 93.344(8), γ = 102.443(6) deg, Z = 4, space group P1-.The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.050 and Rw = 0.065 for 4330 reflections with I >/= 3?(I).The five-membered chelate rings in both of the two crystallographically independent molecules have flattened B-envelope conformations (maximum deviations from the mean planes = 0.114(4) and 0.065(5) Angstroem).Mean bond lengths O-B = 1.553 and C-B = 1.599 Angstroem are consistent with intermediate strength binding of the diphenylboron moiety by the O,O-chelating ligand.

Details of the synthesis and physical properties of the title compound are reported along with a new preparation of 3-benzoyl-(+)-camphor.Crystals of (3-benzoyl-(+)-camphorato)diphenylboron are triclinic, a = 9.0362(3), b = 9.4679(3), c = 14.2731(7) Angst

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