Efficient preparation of 2-azulenylboronate and Miyaura-Suzuki cross-coupling reaction with aryl bromides for easy access to poly(2-azulenyl)benzenes

This paper describes an efficient preparation of 2-azulenylboronate (6) starting from 2-iodoazulene by halogen-metal exchange reaction using n-BuLi and subsequent quenching with 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane. The boronate 6 has been found to undergo Pd-catalyzed Miyaura-Suzuki cross-coupling reaction with a range of aryl bromides including aromatic poly bromides utilizing Pd₂(dba)₃-P(t-Bu)₃ as a catalyst and establishes a strategy to produce novel poly(2-azulenyl)benzenes, some of which are found to be insoluble in common organic solvents, however. The redox behavior of 2-arylazulenes and poly(2-azulenyl)benzenes was examined by cyclic voltammetry (CV) and compared with those of 6-azulenylbenzene derivatives reported previously.     

Kinetics of thermal degradation of poly(aryl ether)s containing phthalazinone and life estimation

New special engineering thermoplastics, poly(phthalazinone ether sulfone) (PPES) and poly(phthalazinone ether sulfone ketone) (PPESK), containing phthalazinone are synthesized through step-polymerization. The kinetics of thermal degradation of PPES and PPESK (1/1) in nitrogen is investigated at several heating rates by thermogravimetry (TG). It is concluded that, based on using Satava’s theory, the thermal degradation mechanism of PPESK (1/1) is nucleation and growth, the order of reaction of the degradation process is one (n = 1). In contrast, the thermal degradation mechanism of PPES is a phase boundary controlled reaction and the order of the reaction is two (n = 2). The kinetic parameters, including reaction energy and frequency factor of thermal degradation reaction for PPES and PPESK (1/1) are analyzed using isoconversional Friedman, Kissinger–Akahira–Sunose (K–A–S) and Ozawa method. In addition, the study focus on the influence of heating rate and ratio of ketone/sulfone on thermal stability and the life estimation are described.     

Selective synthesis of (E)-triethyl(2-arylethenyl)silane derivatives by reaction of aryl bromides with triethyl vinylsilane catalysed by a palladium-tetraphosphine complex

Cis, cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane / 0.5 [PdCl(C₃H₅)]₂ system catalyses the Heck reaction of vinylsilane derivatives with a range of aryl bromides with high ratio substrate/catalyst in good yields. The formation of mixtures of styrene, (E)-triethyl(2-arylethenyl)silane and triethyl(1-arylethenyl)silane derivatives was observed in some cases. Very high selectivities (up to 100%) in favour of the formation of (E)-triethyl(2-arylethenyl)silane derivatives were obtained in the presence of sodium acetate as base. With other bases such as potassium carbonate, the formation of large amounts of styrene derivatives was observed. The reaction tolerates several functions such as fluoro, trifluoromethyl, methoxy, dimethylamino, acetyl, formyl, benzoyl, carboxylate, nitro or nitrile. Moreover, turnover numbers up to 10,000 can be obtained for this reaction.     

Synthesis and characterization of two new aryl cyclobutyl ketoethyl methacrylate monomers and their polymers

Two new methacrylate monomers, 2‐[3‐(6‐tetralino)‐3‐methylcyclobutyl]‐2‐ketoethyl methacrylate (TKEMA) and 2‐(3‐mesityl‐3‐methylcyclobutyl)‐2‐ketoethyl methacrylate (MKEMA), were obtained from the reaction of 1‐chloroacetyl‐3‐methyl‐3‐arylcyclobutane with sodium methacrylate. The oxime and hydrazone derivatives of poly(TKEMA) and poly(MKEMA) were prepared with hydroxylamine and 2,4‐dinitrophenyl hydrazine. Poly(TKEMA) and poly(MKEMA), their oxime and hydrazone derivatives, and the monomers were characterized with Fourier transform infrared and NMR techniques. The glass‐transition temperatures and thermal stability of the polymers and their oxime and hydrazone derivatives were compared. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4167–4173, 2001     

Aryl 2-thienyl sulfides and aryl 2-thienyl sulfones

A method was developed for the synthesis of the previously unknown aryl 2-thienyl sulfides; the method is based on the reaction of 2-chlorothiophene and its derivatives with thiophenols in the gas phase at 450–500°C. The synthesized sulfides were oxidized to the corresponding aryl 2-thienyl sulfones, which were also previously unknown. 2,5-Dichlorothiophene reacts with excess thiophenol to give 2,5-bis(phenylthio)thiophene, which is oxidized to the corresponding disulfone.     

Synthesis of new aryl substituted furan-2(5H)-ones using the Suzuki-Miyaura reaction

A series of novel 5-arylidenefuran-2(5H)-ones and 5-arylidene-4-arylfuran-2(5H)-ones were synthesized via the Suzuki-Miyaura reactions of fimbrolide derivatives 5-(bromomethylene)furan-2(5H)-one and 4-bromo-5-(bromomethylene)furan-2(5H)-one, respectively. A regioselective Suzuki-Miyaura reaction on 4-bromo-5-(bromomethylene)furan-2(5H)-one allowed the synthesis of unsymmetrically substituted 5-arylidene-4-arylfuran-2(5H)-ones. The crystal structure of the intermediate 5-arylidene-4-bromofuran-2(5H)-one revealed interesting Br?O halogen bonding.     

Synthesis of 2H-chromenes and 1,2-dihydroquinolines from aryl aldehydes, amines, and alkenylboron compounds

The one-step reaction of salicylaldehydes with amines and alkenyl boronic acids or alkenyl trifluoroborates to form 2H-chromenes (2H-1-benzopyrans) has been investigated in more detail and new suitable conditions have been identified, including the use of tertiary amines and protic solvents including water. This process was applied to a concise synthesis of a tocopherol analog. The analogous condensation reaction between 2-sulfamidobenzaldehydes and alkenyl trifluoroborates provides an efficient synthesis of 1,2-dihydroquinoline derivatives.     

Synthesis and antifungal property of N-(aryl) and quaternary N-(aryl) chitosan derivatives against Botrytis cinerea

A series of N-(aryl) and their quaternary N-(aryl) chitosan derivatives were synthesized and evaluated for their antifungal activity against crop-threatening fungus Botrytis cinerea. Schiff bases were firstly synthesized by the reaction of chitosan with cinnamaldehyde, cuminaldehyde and 4-dimethylaminobenzaldehyde followed by reduction with sodium borohydride to form N-(aryl) chitosans. Quaternary N-(aryl) chitosans were then obtained by reaction of N-(aryl) chitosan compounds with ethyl iodide. The chemical structures were characterized by ¹H-NMR, FT-IR and UV spectroscopic techniques. The antifungal activity was evaluated in vitro against B. cinerea by mycelial growth inhibition method and in vivo by application of compounds to tomato plants prior to inoculation with fungal spores. In an in vitro experiment, all quaternized chitosans were more active than N-(aryl) chitosan derivatives and N,N,N-(diethylcinnamyl) chitosan (QC1) was the most potent (EC₅₀ = 1,147 mg/L) against mecelia however, N,N,N-(diethyl-p-dimethylaminobenzyl) chitosan (QC3) was the most potent (EC₅₀ = 334 mg/L) against spores. In an in vivo study, no disease incidence (0.0 %) was observed with QC1 and QC3 at 1,000 mg/L. Spray liquid chitosan enhanced total phenolics and guaiacol peroxidase in inoculated leaves.     

Fluorogenic derivatization of aryl halides based on the formation of biphenyl by Suzuki coupling reaction with phenylboronic acid

The fluorogenic derivatization method for aryl halide was developed for the first time. This method was based on the formation of fluorescent biphenyl structure by Suzuki coupling reaction between aryl halides and non-fluorescent phenylboronic acid (PBA). We measured the fluorescence spectra of the products obtained by the reaction of p-substituted aryl bromides (i.e., 4-bromobenzonitrile, 4-bromoanisole, 4-bromobenzoic acid ethyl ester and 4-bromotoluene) with PBA in the presence of palladium (II) acetate as a catalyst. The significant fluorescence at excitation maximum wavelength of 275–290 nm and emission maximum wavelength of 315–350 nm was detected in all the tested aryl bromides. This result demonstrated that non-fluorescent aryl bromides could be converted to the fluorescent biphenyl derivatives by the coupling reaction with non-fluorescent PBA. We tried to determine these aryl bromides by HPLC-fluorescence detection with pre-column derivatization. The aryl bromide derivatives were detected on the chromatogram within 30 min without any interfering peak derived from the reagent blank. The detection limits (S/N = 3) for aryl bromides were 13–157 fmol/injection.     

A novel electrochemical conversion of CO2 with aryl hydrazines and paraformaldehyde into 1,3,4-oxadiazol-2(3H)-one derivatives in one step

Using CO₂ to replace phosgene or CO as the C1 synthon, we successfully achieved the one-pot electrochemical synthesis of 1,3,4-oxadiazol-2(3H)-one derivatives via a three-component coupling reaction of CO₂ with aryl hydrazines and paraformaldehyde in an undivided cell. With NaI as the electro-catalyst and t-BuOK as the base, this electrochemical process could be smoothly performed to afford the target products in good to high yields at room temperature.     

The preparation and properties of bulk-heterojunction organic solar cells with indole-containing fulleropyrrolidine derivatives as acceptors

Two indole-containing fullerene derivatives, N-hydrogen-2-[3-(N-2-ethylhexylindolyl)][60]fulleropyrrolidine (EHIHC60P), and N-(2-ethylhexylindolyl))-2-[3-(N-2-ethylhexylindolyl)][60]fulleropyrrolidine (DEHIC60P) were synthesized by the typical Prato reaction. The absorption spectra, electrochemical properties of the two compounds were measured. Inverted solar cells were fabricated with the structure of ITO/ZnO/poly(3-hexylthiophene) (P3HT):fullerene derivatives/MoO₃/Ag. The highest power conversion efficiencies (PCEs) of 3.32% and 3.23% were obtained for P3HT/EHIHC60P and P3HT/DEHIC60P based solar cells at the composite ratio of 1:1 after the active layers were annealed at 150 °C under inert atmosphere, with a open-circuit voltage (V_oc) of 0.66 V and 0.74 V, respectively. For comparison, the device based on P3HT/PCBM at the same conditions showed the PCE of 3.28%, with a V_oc of 0.61 V. The influence on the photovoltaic property of the fullerene derivatives, which was induced by some subtle changes in the chemical structure was compared and discussed.     

Photochemical reactions of β-aminovinyl aryl thioketones

Irradiation of β-aminovinyl aryl thioketones ( 1a-b ) afforded β-aminovinyl aryl ketones ( 2a-b ). 2H-Thiopyran derivatives ( 4a-b ) were obtained when β-aminovinyl phenyl thioketone ( 1a ) was irradiated with methyl acrylate and acrylonitrile. 4H-Thiopyran derivatives ( 6,8 ) were also obtained thermally in the reaction of β-aminovinyl phenyl thioketone ( 1a ) and methyl propiolate and maleic anhydride.     

Hydrated ferric sulfate catalyzed synthesis of 3-[(alkyl/arylthio)(aryl)methyl]-1H-indole derivatives through one-pot reaction

A wide variety of 3-[(alkyl/arylthio)(aryl)methyl]-1H-indole derivatives (4a–z) were synthesized through a one-pot three-component reaction from indoles, aromatic aldehydes, and thiols at room temperature using hydrated ferric sulfate as a Lewis acid catalyst. The key features of the present protocol are mild and simple reaction procedure, moderate to good yields, requirement of inexpensive and reusable catalyst, no formation of dithioacetals derivatives from the corresponding aldehydes as well as bis-(indolyl) methane derivatives.     

Fluorescence labeling method for aryl halides with 4-(4,5-diphenyl-1H-imidazol-2-yl)phenylboronic acid based on Suzuki coupling reaction

For the first time, fluorescence labeling methods for aryl halides with a fluorescent arylboronic acid was developed on the basis of a Suzuki coupling reaction. 4-(4,5-diphenyl-lH-imidazol-2-yl)phenylboronic acid (DPA) was used as a fluorescence labeling reagent. In order to explore its analytical performance, the reaction conditions were optimized using simple bromobenzene derivatives. The reactivity was then investigated with chloro- and iodobenzene derivatives, and also bromobenzene derivatives with different position of substituents. The order of reactivity with DPA: iodobenzene > bromobenzene more more than chlorobenzene derivatives, and p- > m- > o-substituted bromobenzenes. The detection limits of bromobenzene, 4-bromotoluene, and 4-bromoanisole ranged from 0.2 to 1.4 pmol/injection at a signal-to-noise ratio, (S/N) of 3. The applicability of the method to biological samples was also evaluated using clofibrate as the analyte. The reaction was found not only to proceed well but also to be selective for clofibrate even in the presence of plasma components. The method allowed the sensitive detection of clofibrate in human plasma with the detection limit of 170 pmol/mL (260 fmol/injection) at a S/N = 3. The proposed method is highly selective and sensitive and thus would be useful for labeling of aryl halides that do not have other functional groups that could be labeled by currently available fluorescent labeling reagents.     

Lewis-acid-catalyzed rearrangement of arylvinylidenecyclopropanes: significant influence of substituents and electronic nature of aryl groups

Lewis-acid-catalyzed reactions of arylvinylidenecyclopropanes having three substituents at the corresponding cyclopropyl rings have been investigated thoroughly. The reaction products are highly dependent on the substituents at the corresponding cyclopropyl rings and the electronic nature of the aryl groups. For arylvinylidenecyclopropanes bearing two alkyl groups at the C-1 position (R1, R2, R3=aryl; R4=H; R5, R6=alkyl), naphthalene derivatives were formed in the presence of Lewis-acid Eu(OTf)3 in DCE at 40 degrees C. For arylvinylidenecyclopropanes in which R1, R2, R3=aryl and R4, R5=alkyl (syn/anti isomeric mixtures), the corresponding 6aH-benzo[c]fluorine derivatives were formed in the syn-configuration via a double intramolecular Friedel-Crafts reaction when all of the aryl groups do not have electron-withdrawing groups or the corresponding indene derivatives were obtained via an intramolecular Friedel-Crafts reaction as long as one electron-deficient aryl group was attached. For arylvinylidenecyclopropanes in which R1, R2, R3, R4=aryl and R5=alkyl or H, the corresponding indene derivatives were obtained exclusively via a sterically demanding intramolecular Friedel-Crafts reaction. Lewis-acid effects and mechanistic insights have been discussed on the basis of experimental investigations.     

Formation of 3-[amino(aryl)-methylidene]-1,3-dihydro-2H-indol-2-ones involving ring transformation of 2-aryl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazoles

The reaction of 3-bromooxindole with substituted (hetero)aromatic thioamides in acetonitrile was studied. At room temperature the reaction preferably gives products of ring transformation i.e. 2-aryl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazoles (3b-f,h) whereas at elevated temperature products of an Eschenmoser coupling reaction, i.e. 3-[amino(aryl)-methylidene]-1,3-dihydro-2H-indol-2-ones (2b-f), are formed exclusively. There exist only two exceptions (4-methoxy and 2-pyridinthioamide) in which the Eschenmoser coupling reaction always takes place giving 2a and 2g. Also N-methylation of the starting 3-bromooxindole completely prevents formation of thiazoles. The prepared thiazoles 3b-f are unstable in solution and they undergo slow ring transformation to 2b-f. The rate limiting step of this rearrangement involves cleavage of an intermediary thiirane ring, which is slowed down by electron-withdrawing substituents on the thioamide (ρ = ?1.15).     

MNPs@SiO2‐Pr‐AP: A new catalyst for the synthesis of 2‐amino‐4‐aryl thiazole derivatives

A simple and efficient synthesis of 2‐amino‐4‐aryl thiazole derivatives was carried out through the reaction of substituted acetophenones and thiourea using three different types of catalytic systems including N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonamide [TBBDA], poly(N,N′‐dibromo‐N‐ethylbenzene‐1,3‐disulfonamide) [PBBS] and a combination of TBBDA and nano‐magnetic catalyst supported with functionalized 4‐amino‐pyridine silica (MNPs@SiO₂‐Pr‐AP). The results showed that the use of TBBDA along with the MNPs@SiO₂‐Pr‐AP gains the highest yields of the products in the shortest reaction time.     

Novel capto-dative (Z,E)-2-(alkylthio)alk-2-en-4-ynals: synthesis and heterocyclization

An efficient synthesis of new (Z,E)-2-(alkylthio)alk-2-en-4-ynals by aldol condensation reaction of ynals with (alkylthio)-acetaldehydes using NaOH/DMF system has been developed.The reaction of these products with N,N-diphenylethylene-diamine and p-tosylmethyl isocyanide proceeds at the carbonyl group to form the corresponding imidazolidine and oxazole derivatives.     

Palladium-catalyzed highly regioselective and stereoselective arylation of electron-rich allylamines with aryl bromides

A palladium-catalyzed, highly efficient Heck arylation of electron-rich N,N-diprotected allylamine derivatives with a wide range of aryl bromides under ligand-free conditions has been developed. In the presence of Pd(OAc)₂ and an appropriate additive, the reaction proceeds with excellent regioselectivity and stereoselectivity, leading exclusively to the γ-arylated (E)-allylamine products in good to excellent yields. It was found that the choice of solvent, olefin, additive and temperature has an important influence on the reaction. Worthy of note is that good results were observed only when using N,N-diprotected allylamines containing carbamate moiety, and the steric properties of allylamines also have important impacts on the regiocontrol. The use of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) or HQ (hydroquinone) as the additive is also crucial for securing a faster reaction rate. This method provides a straightforward approach for the efficient synthesis of various γ-arylated, linear (E)-allylamines.     

Synthesis of dialkyl 5-(aryl)-1-phenyl-1H-prazole-3,4-dicarboxylates via a one-pot and four-component reaction

A number of new dialkyl 5-(aryl)-1-phenyl-1H-prazole-3,4-dicarboxylate derivatives have been prepared regiospecifically in moderate to good yield from the cyclocondensation reaction of dialkyl (E)-2-(dialkoxyphosphoryl)-3-(aroyl)-2-butenedioate, derived from the reaction between trimethyl phosphite, an acetylenic ester, and an aroyl chloride, with phenylhydrazine. The reaction is four-component and is carried out under reflux conditions in dry toluene.