BF3-promoted synthesis of spiroindenyl heterocycles

An easy and straightforward synthesis of spiroindenyl heterocycles by the repeated treatment of boron trifluoride etherate (BF₃-OEt₂) is reported. The overall transformation from ketones 1 to spiro-fused indenes 3 proceeds via Wittig olefination, deconjugation, Grignard addition, and intramolecular electrophilic cyclization in moderate yields. It presents a novel rearrangement reaction catalyzed by boron trifluoride etherate and broadens the scope of application.     

BF3‐OEt2‐Mediated Rearrangement of (4‐Phenylpiperidin‐4‐Yl)‐Arylmethanols

Synthesis of several 4‐benzhydrylidenepiperidine analogs has been established starting from different (4‐phenylpiperidin‐4‐yl)‐arylmethanols via boron trifluoride etherate mediated rearrangement. The possible rearranged mechanism was proposed. Boron trifluoride etherate‐mediated rearrangement of the related derivatives was also examined. It presents a novel rearrangement reaction catalyzed by boron trifluoride etherate and broadens the scope of application.     

New synthesis of 3-arylpyrrolines

We present an easy and straightforward synthesis of 3-arylpyrrolines 4a-g by repeated treatment of 4-aryl-1,2,5,6-tetrahydropyridines 2a-g with m-chloroperoxybenzoic acid (MCPBA) and boron trifluoride etherate (BF₃-OEt₂). The transformation proceeds via epoxidation, ring contraction, Baeyer-Villiger oxidation and elimination reaction and affords 3-arylpyrrolines 4a-g with 61-70% yield. This facile strategy was also used to synthesize racemic baclofen (6).     

Low-potential electrosynthesis of conducting and electroactive oligocatecholborane with blue light-emitting properties

Novel conducting oligocatecholborane (OCOB) with electrical conductivity of 3.73 × 10-2S cm-1 was successfully synthesized by low-potential electropolymerization of catecholborane (COB) in boron trifluoride diethyl etherate at 0.70 V versus Ag/AgCl. FT-IR and 1H-NMR spectra, together with the computational results, proved that COB was polymerized through the coupling at C(4) and C(5) positions and the reactive B―H bond was stable during the electrochemical polymerization. The resulting product was mainly composed of oligomers with short chain lengths by GPC and mass spectral results. The as-formed OCOB film showed good electrochemistry in monomer-free electrolytes with the electrochromic property from opaque blue to sap green. Fluorescence studies indicated that soluble OCOB can emit bright blue light under excitation of 365 nm UV light with the maximum emission at 396 nm and a fluorescence quantum yield of 0.21. The deposited OCOB also exhibited favorable thermal stability and smooth and compact morphology even at high magnifications.     

Low potential electrosyntheses of free-standing polyfluorene films in boron trifluoride diethyl etherate

High quality free-standing polyfluorene (PFe) films were synthesized electrochemically by direct anodic oxidation of fluorene in pure boron trifluoride diethyl etherate (BFEE) on stainless steel sheet. The oxidation potential of fluorene in this medium was measured to be only 1.1 V versus SCE, which was much lower than that determined in acetonitrile + 0.1 mol L⁻¹ TBATFB. PFe films obtained from this medium showed good electrochemical behavior, good thermal stability with conductivity of 0.25 S cm⁻¹, indicating that BFEE is a better medium than acetonitrile for the electrosyntheses of PFe films. FTIR and ¹H NMR spectral investigations indicated that the polymerization of fluorene occurred mainly at 2, 7 position. As-formed PFe films can be partly dissolved in acetone, acetonitrile, tetrahydrofuran, etc.     

Chemoselective S-benzylation of indoline-2-thiones using benzyl alcohols

Indoline-2-thiones were chemoselectively S-benzylated using a variety of benzyl alcohols by boron trifluoride etherate-catalyzed reactions. The aryl substituent effect on the reactivity of the benzyl alcohols toward S-benzylation is also discussed.     

Improved synthesis of sterically encumbered multibrominated corroles

Efficient and easily reproducible synthesis of sterically hindered multibrominated corroles is achieved via dipyrromethane-aldehyde condensation reaction in good yields.Boron trifluoride dietherate（BF_3-Et_2O） is found to be the effective catalyst for cyclization reaction,giving corrole as the major product.     

ELECTROCHEMICAL COPOLYMERIZATION OF 3-（4-FLUOROPHENYL）THIOPHENE AND 3-METHYLTHIOPHENE IN BORON TRIFLUORIDE DIETHYL ETHERATE

The copolymer poly（3-（4-fluorophenyl）thiophene-co-3-methylthiophene） was successfully prepared from mixtures of 3-（4-fluorophenyl）thiophene （FPT） and 3-methylthiophene （MET） via electrochemical oxidation in boron trifluoride diethyl etherate （BFEE） and its mixed electrolytes with acetonitrile （ACN）. The influence of monomer concentration ratios on the copolymerization was investigated by using linear sweep voltammetry and cyclic voltammetry. The structure and morphology of these copolymer films were elucidated by UV-Vis, infrared spectroscopy, elemental analysis, thermal analysis and scanning electron microscopy （SEM）, respectively. The results showed that the molar ratio of FPT and MeT units, when copolymer was electrodeposited from feed ratio of FPT：MeT = 1：2, was about 1.08：1. In addition, the introduction of ACN into BFEE has little effect on the properties of as-formed copolymers.     

四氢呋喃/三氟化硼乙醚混合电解质中咔唑的电化学聚合

在四氢呋喃/三氟化硼乙醚混合电解质中直接阳极氧化咔唑制备聚咔唑.单体的起始氧化电位为0.92 Vversus SCE,远低于单体在含0.1 mol.L-1Bu4NBF4的乙腈溶液中的起始氧化电位(1.36 Vversus SCE).在此体系中获得的聚咔唑膜具有良好的电化学活性和稳定性,其电导率为7.0×10-3S.cm-1.聚合物可部分溶解于二甲基亚砜等强极性有机溶剂.UV-Vis,FT-IR,1H-NMR证明聚合物共轭长链的形成.该体系中获得的聚咔唑是一种蓝光发射材料,并具有良好的热稳定性.     

F3B · OEt2‐Promoted Intramolecular Si to C Phenyl Group Migration: A Highly Diastereoselective Synthesis of (4S,5S)‐4‐Hydroxy‐5‐phenyl‐2‐pyrrolidinone

A highly diastereoselective approach to N‐protected cis‐(4S,5S)‐4‐hydroxy‐5‐phenyl‐2‐pyrrolidinone is reported. The key step is a boron trifluoride etherate–promoted chemoselective intramolecular Si→C phenyl group migration.     

聚吲哚及其衍生物的荧光光谱

在三氟化硼乙醚及其混合电解质中,吲哚及其衍生物阳极氧化可以获得高质量的聚吲哚及其衍生物膜:聚吲哚、聚(5-甲基吲哚)、聚(5-硝基吲哚)、聚(5-氰基吲哚)、聚(5-溴吲哚).它们可溶于DMSO和THF中.聚吲哚及其衍生物具有良好的荧光性质;单体的发射光谱与取代基有关,而聚合物的发射光谱几乎不受取代基的影响.电子离域程度增大,使得聚合物的激发和发射光谱红移,宽的分子量分布则会使聚合物的激发和发射光谱变宽.     

三氟化硼乙醚溶液中卤代芴的电化学聚合

在三氟化硼乙醚(BFEE)溶液中9-溴芴和9,9-二氯芴可以直接阳极氧化制备聚(9-溴芴)和聚(9,9-二氯芴).单体在BFEE中的起始氧化电位远低于在乙腈体系中的起始氧化电位.聚(9-溴芴)和聚(9,9-二氯芴)均可溶于强极性有机溶剂,如二甲基亚砜、四氢呋喃等,并分别表现出良好的蓝色和黄绿色发光性能,其电导率测定为10-1S/cm.红外光谱和核磁共振波谱表明聚合反应主要发生在2,7位.     

1,8-亚乙基萘在三氟化硼乙醚-聚乙二醇中的电化学聚合

在三氟化硼乙醚(BFEE)-聚乙二醇(分子量400,PEG400)混合电解质溶液中,1,8-亚乙基萘直接阳极氧化聚合可以获得自支撑聚(1,8-亚乙基萘)膜.单体在三氟化硼乙醚+10%PEG400中的起始氧化电位为0.95 Vversus SCE,远低于单体在0.1 mol.L-1四氟化硼四丁基胺-乙腈溶液中的起始氧化电位(1.38 VversusSCE).同时PEG400的加入可以有效改善单体在三氟化硼乙醚中的溶解性.UV-Vis,FTIR和1H-NMR确定了1,8-亚乙基萘在4,5位聚合,荧光光谱表明固态及可溶聚(1,8-亚乙基萘)膜是蓝色发光材料.     

ELECTROCHEMICAL POLYMERIZATION OF 5-CYANOINDOLE IN MIXED ELECTROLYTES OF BORON TRIFLUORIDE DIETHYL ETHERATE AND DIETHYL ETHER

High quality poly（5-cyanoindole） （P5CI） films were electrosynthesized by direct anodic oxidation of 5-cyanoindole on stainless steel sheet in the mixed electrolytes of boron trifluoride diethyl etherate （BFEE） and diethyl ether （EE） （by volume 1：1） ＋ 0,05 mol L^-1 Bu4NBF4. The film formed can be peeled off the electrode into freestanding films, The addition of EE into BFEE can improve the solubility of monomer. P5CI films obtained from this medium showed excellent electrochemical behavior with conductivity of 10^-2 S cm^-1, Structural studies showed that the polymerization of 5-cyanoindole occurred at the 2,3 position. As-formed P5CI films were thoroughly soluble in strong polar organic solvent dimethyl sulfoxide （DMSO） while partly soluble in tetrahydrofuran （THF） or acetone. Fluorescence spectral studies indicated that P5CI was a good blue-ight emitter.     

Low-potential facile electrosyntheses of free-standing poly(5-methoxyindole) film with good fluorescence properties

High-quality free-standing poly(5-methoxyindole) (P5MIn) films were synthesized electrochemically by direct anodic oxidation of 5-methoxyindole (5MIn) in boron trifluoride diethyl etherate (BFEE). P5MIn films obtained from this medium showed good electrochemical behavior and good thermal stability with a conductivity of 0.12 S cm⁻¹. P5MIn films were insoluble in water, acetone and tetrahydrofuran. The structure of the polymer was studied by UV–visible spectroscopy and FT-IR spectroscopy, which indicated that the polymerization occurred at C₍₂₎ and C₍₃₎ position. Fluorescent spectral studies indicate that solid P5MIn film is a good blue emitter. Thermal stability of P5MIn film is higher than poly(5-methylindole) and poly(5-chloroindole) obtained from BFEE. To the best of our knowledge, this is the first report on the electrosyntheses of free-standing P5MIn films.     

ELECTROCHEMICAL COPOLYMERIZATION OF DIBENZOFURAN AND 3-METHYLTHIOPHENE IN BORON TRIFLUORIDE DIETHYL ETHERATE

The copolymerization of dibenzofuran(DBF)and 3-methylthiophene(MET)was successfully achieved electrochemically by direct anodic oxidation of the monomer mixtures in boron trifluoride diethyl etherate.The effects of applied polymerization potential and the monomer concentration ratios on the copolymerization were investigated by linear sweep voltammetry and cyclic voltammetry(CV).The structure of copolymer films were investigated by UV-Vis,infrared spectroscopy,thermal analysis.As-formed novel copolymers ...     

Electrosyntheses and characterization of poly(9-bromophenanthrene) in boron trifluoride diethyl etherate

A novel semi-conducting polymer poly(9-bromophenanthrene) (P9BP) was synthesized electrochemically by direct anodic oxidation of it is monomer 9-bromophenanthrene (9BP) in boron trifluoride diethyl etherate (BFEE). The oxidation onset potential of 9BP in this medium was measured to be only 1.33 V vs. saturated calomel electrode (SCE). P9BP films obtained from BFEE showed good electrochemical behavior and nice thermal stability with electrical conductivity of 0.03 S cm⁻¹. FTIR and ¹H NMR spectra together with theoretical quantum chemistry calculations indicated that the P9BP was mainly grown via the coupling of the monomer at C₃ and C₆ positions. Furthermore, P9BP exhibited strong electrochromic nature from opaque green to light yellow between the doped and dedoped states on ITO electrode in solid state. Fluorescence spectral studies indicated that P9BP was a blue light emitter.     

Direct electrosynthesis and characterization of a new soluble polyfluorene derivative containing carboxyl group in boron trifluoride diethyl etherate

High-quality poly(fluorene-9-acetic acid) (PFAA), a new soluble polyfluorene derivative, was synthesized electrochemically by direct anodic oxidation of fluorene-9-acetic acid (FAA) in boron trifluoride diethyl etherate (BFEE) containing a certain amount of trifluoroacetic acid (TFA). This electrolyte enables facile anodic oxidation of FAA monomer at lower potential (1.05 V vs. SCE). PFAA films with conductivity of 0.53 S cm⁻¹ obtained from this medium showed better redox activity and thermal stability in relation to unsoluble poly(fluorene-9-carboxylic acid). Fluorescent spectral studies indicate that PFAA film with high fluorescence quantum yields and photochemical stability is a good blue-light emitter. The structure and morphology of the polymer were studied by UV–vis, FT-IR, ¹H NMR spectra and scanning electron microscopy, respectively.     

Electrosynthesis of highly conducting poly(1,5-dihydroxynaphthalene) in BF3·Et2O

Direct anodic oxidation of 1,5-dihydroxynaphthalene (DHN), an important derivative of naphthalene, led to the formation of high-quality semiconducting poly(1,5-dihydroxynaphthalene) (PDHN) on stainless steel sheets in boron trifluoride diethyl etherate (BFEE). The onset oxidation potential of DHN in this medium was measured to be only 0.78 V vs. SCE, which was lower than that determined in traditional acetonitrile containing 0.1 mol/L tetrabutylammonium tetrafluoroborate (0.98 V vs. SCE). As-formed PDHN films showed good redox activity and stability, together with interesting electrochromic property from brown (doped) to yellow-green (dedoped). Structural characterization, including FTIR, ¹H NMR, and quantum chemistry calculations, indicated that the polymerization of DHN probably occurred at C₄ and C₈ positions. Moreover, thermal analysis revealed that PDHN displayed better thermal stability than that synthesized by chemical method. The fluorescence spectral studies, together with the electrical tests, showed that PDHN was a good blue light-emitter (fluorescence quantum yield higher than 0.1) with an electrical conductivity of as high as 0.46 S/cm.     

Lactonization of 5-Phenylfuran-4-arylcarbinol-3-carboxylic Acids under the Catalysis of Boron Trifluoridc Etherate

Manykindso贯naturalproductswhichhaveamoietyoflactoneringexhibitvariousbiologicalactlvltles,andsometuroturanllgnanstallIntothiscategoryl！nourcontinuousstudyofmrofuranllgnans,wehaverecentlydescribedaconvenientmethodforthesynthesiso贡5－phenyl－4－aroylfuran－3－carboxyllcacidsl－．Toaccomplishthesynthesisof在heanalogof山elactoneH9＂ans,山ehydroxyacids2,whichwereobtainedInexcel！entyieldso笆approximationgi％fromthereductionofketoacidslInaqueousalkalinesolutionsofNaBH。（reflux,4h）,mustb…