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International audience; Boratranes synthesis are predictably based on the reactions of triethanolamine derivatives with boric acid, or trialkyl borate and require prolonged heating of the reagents under reflux. Herein, the authors report an efficient synthesis of unexpected boratranes featuring on one hand three six-membered chelating ring or two six-membered and one five-membered chelating ring and on the other hand a trans-annular boron atom is bound to one nitrogen, two oxygen and one carbon atom. These novel boratranes have been synthetized by reacting N,N-bis(2-methoxybenzyl) alkynylamines with BBr3 in dichloromethane at low temperature. The reaction mechanism was investigated by using density functional theory (DFT) calculations. A mechanistic pathway proceeding through a key dioxazaborecinium intermediate was proposed. This alternative protocol represents a convenient access to dissymmetric and functionalizable boratranes under mild conditions in good yields.

Boron tribromide and aryldihaloboranes were found to undergo 1,3-haloboration across one W-N≡N moiety of a group 6 end-on dinitrogen complex (i.e. trans-[W(N2 )2 (dppe)2 ]). The N-borylated products consist of a reduced diazenido unit sandwiched between a WII center and a trivalent boron substituent (W-N=N-BXAr), and have all been fully characterized by NMR and IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Both the terminal N atom and boron center in the W-N=N-BXAr unit can be further derivatized using electrophiles and nucleophiles/Lewis bases, respectively. This mild reduction and functionalization of a weakly activated N2 ligand with boron halides is unprecedented, and hints at the possibility of generating value-added nitrogen compounds directly from molecular dinitrogen.

The mechanism of acetylene bromoboration in neat boron tribromide was studied carefully by means of experiment and theory. Besides the syn-addition mechanism through a four-center transition state,...

Although radical formation from a trialkylborane is well documented, the analogous reaction mode is unknown for trihaloboranes. We have discovered the generation of bromine radicals from boron tribromide and simple proton sources, such as water or tert-butanol, under open-flask conditions. Cyclopropanes bearing a variety of substituents were hydro- and deuterio-brominated to furnish anti-Markovnikov products in a highly regioselective fashion. NMR mechanistic studies and DFT calculations point to a radical pathway instead of the conventional ionic mechanism expected for BBr3., Anti-Markovnikov hydrobromination of cyclopropanes was achieved using boron tribromide and water as the bromine and proton sources, respectively.

In this paper, the relationship between coordination complexes and electrical properties according to the bonding structure of boron and silicon was analyzed to optimize the p–n junction quality for high-efficiency n-type crystalline solar cells. The p+ emitter layer was formed using boron tribromide (BBr3). The etch-back process was carried out with HF-HNO3-CH3COOH solution to vary the sheet resistance (Rsheet). The correlation between boron–silicon bonding in coordination complexes and electrical properties according to the Rsheet was analyzed. Changes in the boron coordination complex and boron–oxygen (B–O) bonding in the p+ diffused layer were measured through X-ray photoelectron spectroscopy (XPS). The correlation between electrical properties, such as minority carrier lifetime (τeff), implied open-circuit voltage (iVoc) and saturation current density (J0), according to the change in element bonding, was analyzed. For the interstitial defect, the boron ratio was over 1.8 and the iVoc exceeded 660 mV. Additional gains of 670 and 680 mV were obtained for the passivation layer AlOx/SiNx stack and SiO2/SiNx stack, respectively. The blue response of the optimized p+ was analyzed through spectral response measurements. The optimized solar cell parameters were incorporated into the TCAD tool, and the loss analysis was studied by varying the key parameters to improve the conversion efficiency over 23%.

p-tert-Butylcalix[6]arene hexamethyl ether was oxidized in one step to the corresponding ketocalix[6]arene via photochemical bromination (100 W spot lamp) with NBS in a chloroform/water mixture. A pentamethyl ketocalix[6]arene derivative was obtained by reaction of the ketocalix[6]arene hexamethyl ether with boron tribromide dimethyl sulfide complex, and characterized by X-ray crystallography. In the presence of base, the compound undergoes an intramolecular nucleophilic aromatic substitution reaction.

The crucible-free reaction between heated tungsten wires and gaseous boron tribromide yields different tungsten borides. The experiments were carried out at various reaction temperatures and times, revealing the formation of W2 B, WB and WB2 phases. The underlying reactions were analyzed by using thermodynamic model calculations. The stability of the gaseous tungsten bromides was evaluated using quantum chemical methods. While the developed synthesis of phase-pure borides is only possible to a limited extent, it offers a potential route for a formation of protective coatings with high chemical and thermal resistance.

During optimization of the synthesis of the mixed μ opioid agonist/δ opioid antagonist 5-(hydroxymethyl)oxymorphone (UMB425) for scale-up, it was unexpectedly discovered that the 4,5-epoxy bridge underwent rearrangement on treatment with boron tribromide (BBr3) to yield a novel opioid with a little-studied pyranomorphinan skeleton. This finding opens the pyranomorphinans for further investigations of their pharmacological profiles and represents a novel drug class with the dual profile (μ vs δ) predicted to yield lower tolerance and dependence. The structure was assigned with the help of 1D, 2D NMR and the X-ray crystal structure.

BBr3 -assisted chiral phosphoric acid catalysts for enantioselective [2+2] cycloaddition were developed. The reactions of phenyl vinyl sulfide with α-substituted acroleins proceeded, and the corresponding [2+2] cycloadducts were obtained with high enantioselectivity. In particular, the [2+2] cycloadduct obtained from methacrolein is a synthetically useful optically active cyclobutane, which could be transformed to a key intermediate for (+)-frontalin, a pheromone of Asian elephants.

This study gives an account of an innovative, crucible-free technique for the synthesis of single-phase borides at relatively moderate temperatures. A metal wire heated by an electrical current reacts with a chosen gaseous boron halide in a gas/solid reaction yielding a single-phase, oxygen- and carbon-free product, as evidenced by X-ray powder diffraction and chemical analysis. This method is demonstrated using the example of hafnium reacting with boron tribromide. Preliminary thermodynamic considerations show that this kind of crucible-free synthesis specifically enables the preparation of borides of transition metals and similar elements.

The single-step reaction of benzene and boron tribromide in a closed reactor at elevated temperature (800 °C) results in the synthesis of bulk boron-doped graphitic carbon. Materials of continuously tunable composition BCx′ are accessible (x ≥ 3), exhibiting the structure of a solid-solution of boron within turbostratic graphite (G′). Upon extended heat treatment or at higher temperatures, graphitic BCx′ is leached of boron and undergoes a phase separation into boron carbide and graphite. Higher boron content is correlated with an increased maximum capacity for alkali metal ions, making graphitic BCx′ a promising candidate anode material for emerging sodium-ion batteries.

The first synthesis of nepetoidin B in an overall yield of 17% was achieved in two steps through Baeyer–Villiger oxidation of commercially available 1,5-bis(3,4-dimethoxyphenyl)-1,4-pentadien-3-one with oxone to produce the tetramethylated nepetoidin B, followed by demethylation using boron tribromide.

Resveratrol‐based natural products constitute a valuable source of unique compounds with diverse biological activities. In this report we investigate demethylation strategies to minimize formation of cyclized and dimerized products during the synthesis of viniferifuran and analogues. We found that boron trichloride/tetra‐n‐butylammonium iodide (BCl3/TBAI) is typically more effective than boron tribromide (BBr3). Based on these findings we carried out the first syntheses of dehydro‐δ‐viniferin, resveratrol‐piceatannol hybrid and anigopreissin A. In addition, we have developed a short and efficient route to viniferifuran that was obtained in 13% yield over six steps.

International audience; A series of 1,2‐dimethyl[2.10]metacyclophan‐1‐enes (MCP‐1‐enes) containing different substituent groups has been synthesized to illustrate their conformational behavior. 4,22‐dimethoxy‐1,2‐dimethyl[2.10]MCP‐1‐ene 3 was synthesized by a Grignard coupling reaction, Friedel‐Crafts acylation reactions and McMurry coupling reaction from 1,10‐dibromodecane. The formation of 4,22‐dihydroxy‐1,2‐dimethyl[2.10]MCP‐1‐ene 4 was carried out by demethylation of compound 3 with boron tribromide at room temperature. The syn type conformation of 4 was characterized by X‐ray diffraction and was found to form both intramolecular and intermolecular hydrogen bonds between the two hydroxyl groups. From this reaction an interesting compound [10]tetrahydrobenzofuranophane 5 was afforded on prolonging the reaction time. 5,21‐diformyl‐4,22‐dihydroxy‐1,2‐dimethyl[2.10]MCP‐1‐ene 6 has been prepared from 4,22‐dihydroxy‐1,2‐dimethyl[2.10]MCP‐1‐ene 4 by using the Duff method in the presence of hexamethylenetetramine. Structural analysis by 1H NMR spectroscopy and X‐ray diffraction confirmed that both the solution and the crystalline state of compound 6 adopts an anti‐conformation which forms an intramolecular hydrogen bond between the formyl group and the hydroxyl group, which is an interesting finding for long carbon chain MCP compounds.

Coordination polymerizations of 1-vinylnaphthalene (1VN), 2-vinylnaphthalene (2VN) and 6-methoxy-2-vinylnaphthalene (MVN) are carried out at room temperature by using the half-sandwich scandium precursor FluSiMe3 Sc(CH2 SiMe3 )2 (THF) (1) and the constrained geometry configuration rare-earth metal precursors FluCH2 PyLn(CH2 SiMe3 )2 (THF)n [Flu = C13 H8 , Py = C5 H4 N; Ln = Sc (2a), n = 0; Ln = Lu (2b), Y(2c), n = 1]. Atactic poly(1VN) and perfect syndiotactic poly(2VN) and poly(MVN) are produced by precursors 2a-2c in a controlled way. Treatment of poly(MVN) with boron tribromide at -20 °C provides a syndiotactic poly(6-hydroxy-2-vinylnaphthalene).

International audience; Colorless crystalline 2,6-dibromo-4,8-dimethyl-1,3,5,7-tetraphenylbenzobis(diazaborole) 4 resulted from the cyclocondensation of 3,6-dimethyl-1,2,4,5-tetraphenylaminobenzene 3d with two equivalents of boron tribromide in the presence of calcium hydride. Synthesis of the dark-red crystalline 2-bromo-N,N’-bis(diisopropylphenyl)acenaphtho-1,3,2-diazaborole 7 was effected by the cyclocondensation of 1,2-bis(N-2’,6’-diisopropylphenylimino)acenaphthene (5) and boron tribromide with subsequent sodium amalgam reduction of the initially formed burgundy red diazaborolium salt 6. Compounds 4, 6 and 7 are characterised by elemental analyses, 1H, 11B and 13C NMR spectroscopy, as well as by single X-ray diffraction studies. The electronic structures of 4, 6 and 7 are subject to DFT calculations.

A one-step method to obtain boron emitters for n-type solar cells based on the use of boron tribromide (BBr3) as a dopant source is developed. During this study several experimental parameters are varied. It is observed that besides the diffusion temperature, the nitrogen gas flux and the BBr3 bubbler temperature have a significant impact on the obtained emitter properties. Using the adequate experimental conditions a homogenous boron emitter without boron rich layer (BRL), a sheet resistance of 77 Ω sq−1 and a dark saturation current

BBr3-chiral phosphoric acid complexes are highly effective and practical Lewis acid-assisted Brønsted acid (LBA) catalysts for promoting the enantioselective Diels-Alder (DA) reaction of α-substituted acroleins and α-CF3 acrylate. In particular, the DA reaction of α-substituted acroleins with 1,2-dihydropyridines gave the corresponding optically active isoquinuclidines with high enantioselectivities. Moreover, transformations to the key intermediates of indole alkaloids, catharanthine and allocatharanthine, are demonstrated.

N,N-Dimethylaniline (DMA) was identified as a colorimetric titrant for accurate quantification of boron tribromide (BBr3) solutions. The initial 1:1 DMA/BBr3 Lewis acid–base adduct formed upon addition of the first equivalent of BBr3 is bright blue in color. Addition of catalytic quantities of BBr3 beyond the first equivalent initiates an instantaneous change in the solution from blue to yellow. This methodology will allow for accurate quantification of BBr3 so that proper stoichiometric amounts of BBr3 may be used to facilitate a broad range of organic transformations. Download : Download high-res image (61KB) Download : Download full-size image

The synthesis of O-desmethylangolensin (O-DMA) analogues from methoxy-substituted benzoic acids was described. Treatment of methoxy-substituted benzoic acids with 2 equiv of ethyllithium afforded methoxypropiophenones, which were subsequently transformed to ethyl 2-(methoxyphenyl)propionates via 1,2-rearrangement of the methoxyphenyl group using Pb(OAc)4/HClO4 in triethyl orthoformate. After hydrolysis with KOH, the 2-(methoxyphenyl)propionic acids were reacted with di- 2-pyridyl carbonate to afford 2-pyridyl 2-(methoxyphenyl)propionates, which were acylated with methoxy-substituted phenyl- magnesium bromides to give methoxy-α-methyldesoxybenzoins. The methoxy groups of these compounds were selectively or fully demethylated using boron tribromide to give diverse O-DMA analogues in high yields.

A selective procedure has been developed for the synthesis of 1-chloro(bromo)-substituted borolanes and 2,3-dihydro-1H-boroles by reaction of aluminacarbocycles with boron trihalides BX3 (X = Cl, Br). 3-Substituted 1-chloro(bromo)borolanes and 2,3-dihydro-1H-boroles have been isolated as individual substances, and their structure has been determined.

Boron tribromide source yields high-quality thin films, but high levels of bromine impurities limit the application of the produced boron-containing gallium nitride crystals.

Exposure to estrogen is associated with increased risk of breast and other types of human cancer. One therapeutic goal would be the creation of new molecules that would retain hormonal potency while incorporating features to retard or prevent quinone toxicity. Hence, new structures closely related to ERB-041, a known ERβ selective agonist, were synthesized whereas the phenol ring is substituted with non-quinone forming rings such as pyrazole, 2-pyrimidine-2(1H)-one or pyridine-2(1H)-one. 2-Methyl-5-methoxy-1,3-benzoxazoles (or 1,3-benzothiazole) are key intermediates for the production of the pyrazole and pyrimidine-2(1H)-one analogs. The required 1,3-benzoxazoles were synthesized starting from reduction of 2-nitro-4-methoxyphenols, followed by condensation with trimethyl orthoacetate. Then, the diiminium perchlorate intermediates were prepared from the latter compounds by Vilsmeier–Haack reaction. The reaction of the resulting intermediates with hydrazine hydrate and guanidium chloride afforded the title pyrazole and pyrimidine-2(1H)-ones, respectively. The pyridine analogs were synthesized starting from the reaction of 2-amino-4-methoxyphenols with 6-bromopyridine-3-carboxaldehyde followed by oxidation with DDQ to afford bromopyridines. These compounds were next treated with benzyl alcohol in the presence of potassium tert-butoxide to afford 2-benzyloxypyridine, which in subsequent dealkylation with boron tribromide produced the title pyridine-2-(1H)-ones.

The dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch has attracted interest as a molecular switch for advanced materials and molecular electronics. We report here two synthetic approaches using palladium catalysis for synthesizing dihydroazulene (DHA) photoswitches with thioacetate anchoring groups intended for molecular electronics applications. The first methodology involves a Suzuki coupling using tert-butyl thioether protecting groups. Conversion to the thioacetate using boron tribromide/acetyl chloride results in the formation of the product as a mixture of regioisomers mediated by a ring-opening reaction. The second approach circumvents isomerization by the synthesis of stannanes as intermediates and their use in a Stille coupling. Although fully unsaturated azulenes are formed as byproducts during the synthesis of the DHA stannanes, this approach allowed the regioselective incorporation of the thioacetate anchoring group in either one of the two ends (positions 2 or 7) or at both.

Tris[tetrafluoro-4-(trifluoromethyl)phenyl] borane (BTolF) was prepared by treating boron tribromide with tetrameric F3CC6F4-Cu-I. The F3CC6F4-CuI was generated from F3CC6F4MgBr and copper(I) bromide. Lewis acidities of BTolF evaluated by the Gutmann-Beckett method and calculated fluoride-ion affinities are 9 and 10%, respectively, higher than that of tris(pentafluorophenyl) borane (BCF) and even higher than that of SbF5. The molecular structures of BTolF and BCF were determined by gas-phase electron diffraction, that of BTolF also by single-crystal X-ray diffraction.

Dopamine is a ubiquitous neurotransmitter essential in the proper functioning of the human body. In addition to this critical role, the catecholamine core has shown utility as a scaffold for numerous drugs and in other applications, like metal detection and adhesive materials. Substituents at the 6-position of dopamine's catechol core can modulate its stereoelectronic properties, the acidity of its phenolic hydroxyl groups, and the overall hydrophobicity of the molecule. Herein, we report the synthesis of a series of four novel dopamine analogues substituted at the 6-position of the catechol core. The 1H NMR chemical shift of the aromatic proton meta to the substituent correlated strongly with the Hammett σm constant, confirming the electronic properties of the substituents.

Although highly doped boron selective emitters (SEs) can be formed by using laser doping (LD) from the borosilicate glass remaining after boron tribromide tube diffusion, the dopant concentration is limited. This limitation can be overcome by using a laser-induced forward transfer (DLIFT) approach. In this work, SEs formed by DLIFT and LD are compared to a homogenous tube diffusion (Diff) emitter. We investigated the correlation of the emitter saturation current density ( j 0 e ) and the specific contact resistance $(\rho _{c})$ with the sheet resistance $(R_{{\rm{sheet}}})$ and the laser pulse energy density $(E_{p,d})$ . For passivated emitters, $j_{{0}e}$ of DLIFT and LD emitters was around ten times higher than $j_{{0}e}$ of Diff emitters. For metallized emitters, simulated $j_{{0}e}$ of DLIFT emitters was lower than $j_{{0}e}$ of LD and Diff emitters for $R_{{\rm{sheet}}}\,{\rm{ glt; \,40.0\,\Omega / sq}}$ . Moreover, we show how $j_{{0}e}$ can be further reduced by increasing the surface dopant concentration of the boron emitter and by reducing the laser-induced defects in the silicon crystal. Additionally, the metallization of DLIFT emitters with aluminum–silver paste by screen printing provided low contact resistances between metal and silicon ( ρc < 1.0 mΩ · cm2). Thus, p-type emitters can be optimized by forming an SE with the highly doped boron regions achieved by DLIFT under the screen-printed metallization.

This paper is directed to characterize the boron diffusion process according to the specific resistivity of the Si wafer. N-type Si wafers were used with the specific resistivity of 0.5-3.2 omega-cm, 1.0-6.5 omega-cm and 2.0-8.0 omega-cm. The boron tribromide (BBr3) was used as boron source to create the PN junction on N-type Si wafer. The boron diffusion in N-type Si wafer was characterized by sheet resistance of wafer surface, secondary ion mass spectroscopy measurements (SIMS) and surface life time analysis. The degree of boron diffusion was depended on the variation in specific resistivity and sheet resistance of the bare N-type Si wafer. The boron diffused N-Si wafer exhibited the average junction depth of 750 nm and boron concentration of 1 x 10(19). N-type Si wafer with the different specific resistance considerably affected the boron diffusion length and life time of Si wafer. It was found that the lifetime of boron diffused wafer was proportional to the sheet resistance and resistivity. However, optimization process may necessary to achieve the high efficiency through the high sheet resistance wafer, because the metallization process control is very sensitive.

First, catalysts (Ia) and (Ib) are established as the efficient ones for the cycloaddition of cyclic dienes (II) and (V) with acroleins (III) and acrylate (VII) under slightly different conditions.

Selective functionalizations of aryl CH bonds in 2-arylpyridines have been developed via sequential borylation and aerobic oxidative copper catalysis, and the corresponding aryl halides, sulfones, azides and arylamines were obtained in good yields. The protocol uses cheap and readily available boron tribromide (BBr3) as the borylating reagent, and inorganic salts (potassium iodide, ammonium bromide, sodium alkylsulfinates, sodium azide) as the functional group sources. This method makes functionalizations of aryl CH bonds easy.