Brominated Trihalomethylenones as Versatile Precursors to 3‐Ethoxy, ‐Formyl, ‐Azidomethyl, ‐Triazolyl,and 3‐Aminomethyl Pyrazoles

5‐Bromo[5,5‐dibromo]‐1,1,1‐trihalo‐4‐methoxy‐3‐penten[hexen]‐2‐ones are explored as precursors to the synthesis of 3‐ethoxymethyl‐5‐trifluoromethyl‐1H‐pyrazoles from a cyclocondensation reaction with hydrazine monohydrate in ethanol. 3‐Ethoxymethyl‐carboxyethyl ester pyrazoles were formed as a result of a substitution reaction of bromine and chlorine by ethanol. The dibrominated precursor furnished 3‐acetal‐pyrazole that was easily hydrolyzed to formyl group. In addition, brominated precursors were used in a nucleophilic substitution reaction with sodium azide to synthesize the 3‐azidomethyl‐5‐ethoxycarbonyl‐1H‐pyrazole from the reaction with hydrazine monohydrate. These products were submitted to a cycloaddition reaction with phenyl acetylene furnishing the 3‐[4(5)‐phenyl‐1,2,3‐triazolyl]5‐ ethoxycarbonyl‐1H‐pyrazoles and to reduction conditions resulting in 3‐aminomethyl‐1H‐pyrazole‐5‐carboxyethyl ester. The products were obtained by a simple methodology and in moderate to good yields.     

Design,Synthesis, and Antimicrobial Evaluation of some Novel Pyridine,Coumarin, and Thiazole Derivatives

Treatment of 2‐cyano‐N′‐(1‐(pyridin‐2‐yl)ethylidene)acetohydrazide 1 with aromatic/heterocyclic aldehydes 2a–f gave arylidene derivatives 3a–f . Polysubstituted pyridine derivatives 4a,b were prepared either from reaction of arylidene 3a,b with malononitrile or from reaction of acetohydrazide 1 with arylidenemalononitrile 5a,b . Cyclocondensation of acetohydrazide 1 with salicylaldehyde derivatives and acetylacetone furnished pyrido‐coumarins 6,7 and 2‐pyridone‐3‐carbonitrile 8, respectively. In addition, pyrido‐thiazoles 13 and 15 were obtained through reaction of 2‐(1‐(pyridin‐2‐yl)ethylidene)hydrazinecarbothioamide 11 with hydrazonyl chlorides and α‐haloketones, respectively. The structures of synthesized compounds were elucidated with spectral and elemental data. The antimicrobial activity of the synthesized compounds was studied.     

Efficient Synthesis of Functionalized Thiazoles from Acid Chlorides,Tetramethylthiourea, Ethyl Bromopyruvate,and Ammonium Thiocyanate

An efficient synthesis of ethyl 2‐(dimethylamino)‐1,3‐thiazole‐4‐carboxylates is described via a four‐component reaction between acid chlorides, tetramethylthiourea, ethyl bromopyruvate, and ammonium thiocyanate.     

Interfacial Synthesis,Vol. Ill,Recent Advances,Charles E. Carraher,Jr. and Jack Preston,editors, Marcel Dekker,Inc., New York and Basel, 1982, $65.00

Hydrolyses of p‐nitrophenyl picolinate (PNPP) and p‐nitrophenyl acetate (PNPA) mediated by the micellar catalytic systems of two types of cationic surfactants [cetyltrimethylammonium bromide (CTAB), Gemini dimethylene‐1,2‐bis(cetyltrimethylammonium bromide) (16‐2‐16, 2Br^?)] were investigated spectrophotometrically in the pH range of 7.0–9.0 and 25°C. Also, the effects of several kinds of additives, such as ethanol, cyclodextrins (CDs), on the hydrolytic reactions of PNPP and PNPA were studied systematically. It is noteworthy that: (1) double chain Gemini surfactant micellar system enhanced the hydrolyses of carboxylic acid esters notably compared with single chain surfactant (CTAB) micellar solutions under the same reaction conditions; (2) the apparent rate constants (k _obsd) of PNPP and PNPA hydrolyses increased with the increasing in pH values of reaction media; (3) as additives, ethanol has effect on both PNPP and PNPA hydrolyses, and moreover, the k _obsd for hydrolyses decreased with the increasing contents of ethanol (≤5%) at 25°C and pH 9.00; (4) the presence of CDs [α‐cyclodextrin (α‐CD), β‐cyclodextrin (β‐CD), γ‐cyclodextrin (γ‐CD)], as additives, showed different effects on PNPP and PNPA hydrolyses in different reaction systems.     

A Convenient Synthesis of Functionalized Indenopyrazolones from Indan‐1,2,3‐trione,Benzaldehydes, and Phenylhydrazine

A synthesis of cis‐3‐aryl‐3a,8b‐dihydro‐3a,8b‐dihydroxy‐1‐phenylindeno[1,2‐c]pyrazol‐4(1H)‐ones in good yields from the sequential reaction between benzaldehydes, phenylhydrazine, and indan‐1,2,3‐trione in MeCN is described (Scheme 1).     

One‐Pot Synthesis of 5,7,8,9,9a,10‐Hexahydro‐8‐thioxotetrahydropyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6(1H,3H,5aH)‐triones via a Four‐Component Coupling Reaction of Aldehydes,Amines, Barbituric Acids,and Thiouracil

An efficient one‐pot approach to the synthesis of 5,7,8,9,9a,10‐hexahydro‐8‐thioxopyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6(1H,3H,5aH)‐triones 5 via a four‐component reaction of an aldehyde 1 , an amine 2 , a barbituric acid 3 , and thiouracil ( 4 ) is reported for the first time. This new multicomponent reaction is accomplished in refluxing EtOH in the presence of tungstophosphoric acid (H₃PW₁₂O₄₀) as a catalyst. A variety of hexahydropyrido[2,3‐d : 6,5‐d′]dipyrimidinetrione derivatives were successfully synthesized in excellent yields with this protocol (Table 2).     

Synthesis of maleic anhydride grafted polyethylene and polypropylene,with controlled molecular structures

This article discusses a new chemical route to prepare maleic anhydride (MA) grafted polyethylene and polypropylene polymers with controlled molecular structure, that is, MA grafted content and polymer molecular weight and composition distributions. The chemistry involves a free radical graft reaction of maleic anhydride with poly(ethylene‐co‐p‐methylstyrene) and poly(propylene‐co‐p‐methylstyrene) copolymers. Under a suspension reaction condition, the grafting reaction takes place selectively on the p‐methylstyrene units in the copolymer, due to high reactivity of p‐methyl group and favorable mixing between p‐methylstyrene units and chemical reagents in the swollen amorphous phases. The resulting polymer shows no detectable molecular weight change during the reaction, and the MA grafted content increases with the increase of initiator and p‐methylstyrene concentrations. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1337–1343, 2000     

Enaminones as building blocks in organic synthesis: A novel route to polyfunctionally substituted benzonitriles,pyridines, eneylbenzotriazoles and diazepines

An efficient synthesis of enaminones 1a‐c is reported. Compounds 1a‐c reacted with diefhyl‐3‐amino‐2‐cyanopenten‐1,5‐dicarboxylate ( 3 ) to yield the benzonitriles 6 . On the other hand, the reaction of la‐c with 3‐amino‐2‐cyano‐2‐pentene dinitrile ( 7 ) afforded a mixture of benzonitriles 10 and pyridines 9 . The reaction of la‐c with 3‐aminocrotononitrile 11 has afforded the 4‐substituted‐3‐cyano‐2‐methylpyridines 15a‐c . The reaction of ethylene diamine with la‐c afforded 5‐substituted‐2,3‐dihydro‐lH‐[1,4]diazepines 18a‐c . On the other hand, la‐c reacted with o‐phenylenediamine to yield the 4‐(2‐aminopheynlamino)‐substituted enaminones 21 . Compounds 21 could be converted into the benzotriazolylenones 22 on treatment with sodium nitrite in acetic acid solution.     

The First One‐Pot,Solvent‐Free,Microwave‐Accelerated,Three‐Component Synthesis of Spirothiazolidin‐4‐ones via Staudinger/Aza‐Wittig Coupling/Cyclization

An efficient and rapid, solvent‐free, microwave‐accelerated, one‐pot, three‐component protocol for the synthesis of spirothiazolidin‐4‐ones from organic azides is reported for the first time via Staudinger/aza‐Wittig coupling/cyclization. The solvent‐free approach overcomes the limitations associated with the prevailing solution‐phase methodologies in the case of amines. In particular, its novelty is that it eradicates the vital limitation, i.e., the accumulation of H₂O (by‐product), which is known to affect the yield and rate of the reaction, thus affording the spirothiazolidin‐4‐ones in short reaction times in excellent yields.     

Synthesis of the Indene,THF, and Pyrrolidine Skeletons by Lewis Acid Mediated Cycloaddition of Methylenecyclopropanes with Aldehydes,N‐Tosyl Aldimines,and Acetals

Methylenecyclopropanes (MCPs 1 ) react with aldehydes, N‐tosyl aldimines, and acetals to give the corresponding indene, THF, and pyrrolidine cycloaddition products in the presence of BF₃?OEt₂ under mild reaction conditions. Some special transformations of MCPs 1 with aldehydes have been reported in this paper. A plausible reaction mechanism has been discussed, which is based on a deuterium‐labeling experiment and the Prins‐type reaction mechanism.     

Direct,Sequential, and Stereoselective Alkynylation of C,C‐Dibromophosphaalkenes

The first direct alkynylation of C,C‐dibromophosphaalkenes by a reaction with sulfonylacetylenes is reported. Alkynylation proceeds selectively in the trans position relative to the P substituent to afford bromoethynylphosphaalkenes. Owing to the absence of transition metals in the procedure, the previously observed conversion of dibromophosphaalkenes into phosphaalkynes through the phosphorus analog of the Fritsch–Buttenberg–Wiechell rearrangement is thus suppressed. The bromoethynylphosphaalkenes can subsequently be converted to C,C‐diacetylenic, cross‐conjugated phosphaalkenes by following a Sonogashira coupling protocol in good overall yields. By using the newly described method, full control over the stereochemistry at the P=C double bond is achieved. The substrate scope of this reaction is demonstrated for different dibromophosphaalkenes as well as different sulfonylacetylenes.     

Synthesis,Structure, and Properties of Near‐Infrared [b]Phenanthrene‐Fused BF2 Azadipyrromethenes

A new class of phenanthrene‐fused BF₂ azadipyrromethene (azaBODIPY) dyes have been synthesized through a tandem Suzuki reaction and oxidative ring‐fusion reaction, or a palladium‐catalyzed intramolecular C−H activation reaction. These phenanthrene‐fused azaBODIPY dyes are highly photostable and display markedly redshifted absorption (up to λ =771 nm) and emission bands (λ ≈800 nm) in the near‐infrared region. DFT calculations and cyclic voltammetry studies indicate that, upon annulation, more pronounced stabilization of the LUMO is the origin of the bathochromic shift of the absorption and high photostability.     

Ultrasonic irradiation of the ullmann condensation: Application to the preparation of dioxolo,dioxino, cyclopent,and imidazolo anthranilic acid derivatives

The synthesis of N‐aryl anthranilic acid derivatives bearing dioxolo, dioxino, cyclopent, and imidazolo supplementary ring systems is reported. The Ullmann‐Goldberg condensation of the N‐aryl anthranilic acid is improved in yield and reaction time, compared to conventional heating; by ultrasonic irradiation.     

Facile Synthesis,Characterization, and Fluorescence Studies of Novel Porphyrin Appended Thiazoles

A facile and high yielding synthesis of porphyrin appended thiazoles 5 from the reaction of 5‐(4‐thiocarboxamidophenyl)‐10,15,20‐triphenylporphyrin with α‐bromo ketones has been described. The fluorescence studies of synthesized porphyrin appended thiazoles 5 in chloroform indicate that porphyrin π system is not greatly perturbed by substitution of a thiazole moiety at meso‐phenyl ring even in the excited state.     

Incorporation of azo group at axial position of silatranes: synthesis,characterization and antimicrobial activity

4‐Aminoazobenzene‐derived silatranes bearing urea and aminosuccinimide as linker groups at the axial position are reported. The urea functionality is introduced in a silane ( 2 ) by the rearrangement reaction between 3‐isocyanatopropyltriethoxysilane and 4‐aminoazobenzene. N‐(3‐silatranylpropyl)‐N′‐[(p‐phenyldiazenyl)phenyl]urea and N‐[3‐(3,7,10‐trimethylsilatranyl)propyl]‐N′‐[(p‐phenyldiazene)phenyl]urea were prepared by transesterification reaction of 2 with triethanolamine and trisisopropanolamine, respectively. An efficient method for C? N bond formation is described for the synthesis of 3‐(silatranylpropyl)amino‐N‐[(p‐phenyldiazene)phenyl]pyrrolidine‐2,5‐dione and 3‐[(3,7,10‐trimethylsilatranyl)propyl]amino‐N‐[(p‐phenyldiazene)phenyl]pyrrolidine‐2,5‐dione via aza‐Michael addition reaction of aminopropylsilatranes with 4‐(N‐maleimido)azobenzene under mild conditions. All the compounds were well characterized using elemental analysis, spectroscopic techniques, thermogravimetric analysis and X‐ray diffraction. UV–visible spectroscopy indicates that the 4‐aminoazobenzene‐derived silatranes are capable acetate receptors. The synthesized compounds were screened for possible antimicrobial properties with the results showing a modest activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis of a model cyclic triblock terpolymer of styrene,isoprene, and methyl methacrylate

The synthesis of a model cyclic triblock terpolymer [cyclic(S‐b‐I‐b‐MMA] of styrene (S), isoprene (I), and methyl methacrylate (MMA) was achieved by the end‐to‐end intramolecular amidation reaction of the corresponding linear α,ω‐amino acid precursor [S‐b‐I‐b‐MMA] under high‐dilution conditions. The linear precursor was synthesized by the sequential anionic polymerization of S, I, and MMA with 2,2,5,5‐tetramethyl‐1‐(3‐lithiopropyl)‐1‐aza‐2,5‐disilacyclopentane as an initiator and amine generator and 4‐bromo‐1,1,1‐trimethoxybutane as a terminator and carboxylic acid generator. The separation of the unreacted linear polymer from the cyclic terpolymer was facilitated by the transformation of the unreacted species into high molecular weight polymers by the evaporation of the reaction solvent and the continuation of the reaction under high‐concentration conditions. The intermediate materials and the final cyclic terpolymer, characterized by size exclusion chromatography, vapor pressure osmometry, thin‐layer chromatography, IR and NMR spectroscopy, exhibited high molecular weight and compositional homogeneity. Dilute‐solution viscosity measurements were used as an additional proof of the cyclic structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1476–1483, 2002     

Macromolecular reaction and interdiffusion in a compatible polymer blend, 2. The role of H‐bonding

A theory describing slow macromolecular reaction and interdiffusion in a compatible polymer blend is extended to consider H‐bonding. The known treatments of H‐bonding influence on the free energy of mixing and chains' mobilities are combined to calculate mutual diffusion coefficients in the framework of linear non‐equilibrium thermodynamics. Numerical calculations are performed for a blend of two random copolymers AC and BC to reveal the effect of H‐bonding (between A and B, B and B units) on the interdiffusion profiles. Then, the transformation of A units into B ones is included and the reaction‐diffusion equations are solved with the parameters corresponding to the blend of poly(tert‐butyl acrylate‐co‐styrene) with poly‐(acrylic acid‐co‐styrene) in which the thermal decomposition of tert‐butyl acrylate units takes place. The numerical calculations show that this system is suitable for the experimental verification of theoretical predictions concerning the interplay between macromolecular reaction and interdiffusion in polymer blends.     

Diepoxy[18]annulene(10.0) : (Z,E,Z,E,Z)‐Diepoxy[18]annulen(10.0) – ein hochdynamisches Annulen

Diepoxy[18]annulenes(10.0): ( Z , E , Z , E , Z )‐Diepoxy[18]annulene(10.0) – a Highly Dynamic Annulene The McMurry reaction of (all‐E)‐5,5′‐([2,2′‐bifuran]‐5,5′‐diyl)bis[penta‐2,4‐dienal] ( 13 ) only occurs intramolecularly to give a mixture of the diepoxy[18]annulenes(10.0) 6 and 7 . Tetraepoxy[36]annulene(10.0.10.0) resulting from an intermolecular McMurry reaction is not formed. According to spectroscopic data, 6 is (Z,E,Z,E,Z)‐ and 7 (Z,E,E,Z,E)‐configured. The ¹H‐NMR data confirm that in 6 the (E)‐ethene‐1,2‐diyl bonds (C(11)=C(12) and C(15)=C(16)) rotate around the adjacent σ‐bonds. Beginning at −70°, this rotation freezes, and 6 is becoming a diatropic aromatic ring system. Beside [18]annulene itself, (Z,E,Z,E,Z)‐diepoxy[18]annulene(10.0) 6 is the only hitherto known [18]annulene derivative with dynamic properties.     

Palladium(II)‐Catalyzed Oxidative Cyclization of Allylic Tosylcarbamates: Scope,Derivatization, and Mechanistic Aspects

A highly selective oxidative palladium(II)‐catalyzed (Wacker‐type) cyclization of readily available allylic tosylcarbamates is reported. This operationally simple catalytic reaction furnishes tosyl‐protected vinyl‐oxazolidinones, common precursors to syn‐1,2‐amino alcohols, in high yield and excellent diasteroselectivity (>20:1). It is demonstrated that both stoichiometric amounts of benzoquinone (BQ) as well as aerobic reoxidation (molecular oxygen) is suitable for this transformation. The title reaction is shown to proceed through overall trans‐amidopalladation of the olefin followed by β‐hydride elimination. This process is scalable and the products are suitable for a range of subsequent transformations such as: kinetic resolution (KR) and oxidative Heck‐, Wacker‐, and metathesis reactions.     

Rapid Construction of Structurally Diverse Quinolizidines,Indolizidines, and Their Analogues via Ruthenium‐Catalyzed Asymmetric Cascade Hydrogenation/Reductive Amination

A rapid construction of enantioenriched benzo‐fused quinolizidines, indolizidines, and their analogues by ruthenium‐catalyzed asymmetric cascade hydrogenation/reductive amination of quinolinyl‐ and quinoxalinyl‐containing ketones has been developed. This reaction proceeds under mild reaction conditions, affording chiral benzo‐fused aliphatic N‐heterocyclic compounds with structural diversity in good yields (up to 95 %) with excellent diastereoselectivity (up to >20:1 dr) and enantioselectivity (up to >99 % ee). Furthermore, this catalytic protocol is applicable to the formal synthesis of (+)‐gephyrotoxin.