Synthesis and structural characterization of syndiotactic trans‐1,2 and cis‐1,2 polyhexadienes

The (E) isomer in mixtures of (E) and (Z) 1,3‐hexadiene was polymerized with the system CoCl₂(PⁱPrPh₂)₂‐MAO, a highly active and stereospecific catalyst for the preparation of 1,2 syndiotactic polybutadiene. A new crystalline polymer with a melting point of 109 °C was obtained. The polymer was characterized by IR, NMR (¹³C, ¹H in solution and ¹³C in the solid‐state), X‐ray diffraction, DSC, GPC and it was found to have a trans‐1,2 syndiotactic structure with a 5.18 ± 0.04 Å fiber periodicity. Since only the (E) isomer was polymerized, at the end of the reaction we were able to separate the (Z) isomer, which was ultimately polymerized with CpTiCl₃‐MAO at low temperature, obtaining a low molecular weight, stereoregular polymer that, characterized by IR and NMR methods, was found to exhibit a cis‐1,2 syndiotactic structure, never reported before. Molecular mechanics calculations were carried out on the trans‐1,2 syndiotactic polymer and structural models consistent with the X‐ray diffraction data are proposed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5339–5353, 2007     

Synthesis,characterization, and antidiabetic activity of 6‐methoxyimidazo[1,2‐b]pyridazine derivatives

The present article describes the synthesis, characterization, and antidiabetic activity of 6‐methoxyimidazo[1,2‐b]pyridazine derivatives 7a‐l . The synthetic sequence for the preparation of these derivatives involves the following prominent reactions: (a) Step 1: involves the high‐pressure amination reaction; (b) Step 2: involves the Zinc oxide nanoparticle‐catalyzed cyclization reaction; (c) Step 3: involves the methoxylation; (d) Step 4: involves the bromination reaction; (e) Step 5: involves the Suzuki coupling reaction; (f) Step 6: involves the reduction of the –NO₂ group; (g) Step 7: involves Boc protection of the 1^o amino group (h) Step 8: involves diazotization of the amine group and finally the last of the synthesis (i) Step 9: involves the saponification of the ethyl ester group. Furthermore, the structures of the newly synthesized 6‐methoxyimidazo[1,2‐b]pyridazine derivatives 7a–l were determined using ¹H NMR, ¹³C NMR, and Mass and IR spectroscopic analyses. These derivatives were evaluated for their antidiabetic property and the results revealed that most of the compounds exhibited significant potency. It is worth mentioning that compounds 7b (69.87%), 7f (69.0%), 7h (68.79%), and 7l (68.61%) with substitution R = para‐NH₂, para‐COOH, meta‐NH₂, and meta‐COOH, respectively, showed significant (good) hypoglycemic activity when compared to the standard drug insulin (50 mg/kg b.w) in reducing the blood glucose level.     

Synthesis and antimicrobial activity of 3‐(N‐arylamino)‐2‐phenyl‐naphtho[1,3‐d]‐1,2‐oxaphosphole 2‐oxides

The efficient preparation of cis‐3‐(N‐arylamino)‐2‐phenylnaphtho[1,3‐d]‐1,2‐oxaphosphole 2‐oxides 4 and 5 is described by a three‐component reaction involving phenyldichlorophosphine ( 2 ) 1‐hydroxy‐2‐naph‐thaldehyde/1‐hydroxy‐2‐acetonaphthone ( 1 ) and different substituted amines ( 3 ) in anhydrous benzene. The stereo structure, of the products ( 4 and 5 ), as well as the reaction mechanism of the cyclization is discussed. The title compounds ( 4 and 5 ) were fully characterized by NMR and mass spectral data. Their anti microbial activity was evaluated     

Synthesis of some isomeric quinoxaline derivatives with 6‐azauracil cycle

By diazotization of 3‐(2‐aminophenyl)‐1,2‐dihydroquinoxaline 1c, its 3‐(4‐aminophenyl)‐isomer 2c , 3‐(2‐aminobenzyl)‐1,2‐dihydroquinoxaline‐2‐one 3c and its 3‐(4‐aminobenzyl)‐isomer 4c and by azo coupling of formed diazonium salts with ethyl cyanoacetylcarbamate, corresponding hydrazones ld‐4d were prepared. Cyclization of these compounds afforded compounds containing two heterocyclic rings with acidic N‐H groups in their molecules: 3‐[2‐(5‐cyano‐6‐azauracil‐1‐yl)‐phenyl]‐1,2‐dihydroquinoxaline‐2‐one 1e , its 4‐isomer 2e , 3‐[2‐(5‐cyano‐6‐azauracil‐1‐yl)‐benzyl]‐1,2‐dihydroquinoxaline‐2‐one 3e and its 4‐isomer 4e . The aminoderivative 1c was prepared by the reaction of N‐acetylisatine with o‐phenylenediamine and by hydrolysis of prepared N‐acetylderivative 1a . The aminoderivative 2c was prepared by the condensation of 4‐acetylaminophenylglyoxylic acid with o‐phenylenediamine and by hydrolysis of prepared N‐acetylderivative 2a . The aminoderivative 3c was prepared by the condensation of 2‐nitrophenylpyruvic acid with o‐phenylenediamine and by the reduction of the formed nitroderivative 3b and finally starting aminoderivative 4c was obtained by the condensation of o‐phenylenediamine with 4‐aminophenylpyruvic acid.     

Synthesis and structural characterisation of 4H‐1,3‐benzothiazine derivatives

The ring‐closure reactions of N‐arylthiomethylaroylamide derivatives ( 1a‐g ) in the presence of phospho ‐rus oxychloride gave 2‐aryl‐4H‐1,3‐benzo‐thiazines (2a‐g). 2‐(3‐Chlorophenyl)‐6‐methyl‐4H‐1,3‐benzoth‐iazine ( 2b ) was reduced with Zn to obtain the corresponding 2,3‐dihydro derivative ( 3b ). Potassium permanganate oxidation of 2‐(4‐chlorophenyl)‐2,3‐diethoxy‐4H‐ ( 2e ) and 2‐(2‐fluorophenyl)‐6,7‐diefhoxy‐4H‐1,3‐benzo‐thiazines ( 2g ) gave the corresponding 4‐ones ( 4e,g ). The reactions of 2‐(4‐chlorophenyl)‐6‐mefhyl‐4H‐1,3‐benzofhiazine ( 2c ) with substituted acetyl chlorides led to linearly condensed ß‐lactams ( 5a,b ). The structures of the compounds studied were confirmed by ¹H and ¹³C NMR and by their characteristic mass spectrometric fragmentations.     

Synthesis,properties and crystal structural characterization of diorganotin(IV) derivatives of 2‐mercapto‐6‐nitrobenzothiazole

The diorganotin(IV) dichlorides R₂SnCl₂ (R: Ph, PhCH₂ or n‐Bu) react with 2‐mercapto‐6‐nitrobenzothiazole (MNBT) in benzene to give [Ph₂SnCl(MNBT)] ( 1 ), [(PhCH₂)₂Sn(MNBT)₂] ( 2 ) and [(n‐Bu)₂Sn(MNBT)₂] ( 3 ). The three complexes have been characterized by elemental analysis and IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopies. X‐ray studies of the crystal structures of 1 , 2 and 3 show the following. The tin environment for complex 1 is distorted cis‐trigonal bipyramid with chlorine and nitrogen atoms in apical positions. The structure of complex 2 is a distorted octahedron with two benzyl groups in the axial sites. The geometry at the tin atom of complex 3 is that of an irregular octahedron. Interestingly, intra‐molecular non‐bonded Cl…S interactions and S…S interaction were recognized in the crystallographic structures of 1 and 3 respectively. As a result, complex 1 is a polymer and complex 3 is a dimer. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis of 1‐silacyclopent‐2‐ene derivatives using 1,2‐hydroboration, 1,1‐organoboration and protodeborylation

The reaction of di(alkyn‐1‐yl)vinylsilanes R¹(H₂C═CH)Si(C≡C―R)₂ (R¹ = Me ( 1 ), Ph ( 2 ); R = Bu (a), Ph (b), Me₂HSi (c)) at 25°C with 1 equiv. of 9‐borabicyclo[3.3.1]nonane (9‐BBN) affords 1‐silacyclopent‐2‐ene derivatives ( 3a , 3b , 3c , 4a , 4b ), bearing one Si―C≡C―R function readily available for further transformations. These compounds are formed by consecutive 1,2‐hydroboration followed by intramolecular 1,1‐carboboration. Treated with a further equivalent of 9‐BBN in benzene they are converted at relatively high temperature (80–100°C) into 1‐alkenyl‐1‐silacyclopent‐2‐ene derivatives ( 5a , 5b 6a , 6b ) as a result of 1,2‐hydroboration of the Si―C≡C―R function. Protodeborylation of the 9‐BBN‐substituted 1‐silacyclopent‐2‐ene derivatives 3 , 4 , 5 , 6 , using acetic acid in excess, proceeds smoothly to give the novel 1‐silacyclopent‐2‐ene ( 7 , 8 , 9 , 10 ). The solution‐state structural assignment of all new compounds, i.e. di(alkyn‐1‐yl)vinylsilanes and 1‐silacyclopent‐2‐ene derivatives, was carried out using multinuclear magnetic resonance techniques (¹H, ¹³C, ¹¹B, ²⁹Si NMR). The gas phase structures of some examples were calculated and optimized by density functional theory methods (B3LYP/6‐311+G/(d,p) level of theory), and ²⁹Si NMR parameters were calculated (chemical shifts δ²⁹Si and coupling constants ⁿJ(²⁹Si,¹³C)). Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and molecular structure of novel 4‐aryloctahydropyrido‐[1,2‐c]pyrimidine derivatives

A series of new 4‐aryloctahydropyrido[1,2‐c]pyrimidine‐1,3‐diones 6a,b,d‐h and j were synthesized by intramolecular cyclization of α‐aryl‐α‐(1‐ethoxycarbonyl‐2‐piperidyl)‐acetamide derivatives 5a,b,d‐h and j . The structures of compounds were determined by ¹H and ¹³C nmr spectroscopy. Nmr and X‐ray diffraction data indicate that the configuration at the C4, C4a stereocenters constitute RR and SS pair.     

Synthesis and biological testing of 3‐phenyloctahydro‐pyrimido[1,2‐a]‐s‐triazine derivatives

A series of 46 3‐phenyloctahydropyrimido[1,2‐a]‐s–triazine derivatives were synthesized. This synthesis was performed via iminodimethylation of dialkylated 2‐aminopyrimidinedione synthons by substituted primary arylamines. In vitro pharmacological evaluation of these compounds is reported. One of them exhibited antifungal activity against Microsporum canis (10^?6₅₀10^?5 mol/L), and another showed affinity for serotoninergic 5‐HT_1A and 5‐HT_2b receptors (10^?8₅₀10^?7 mol/L).     

Synthesis and characterization of three dinuclear copper(I) complexes of 1,2‐bis(diphenylphosphino)‐1,2‐dicarba‐closo‐dodecaborane

Three dinuclear copper(I) complexes, [Cu₂(µ‐Cl)₂(1,2‐(PPh₂)₂‐1,2‐C₂B₁₀H₁₀)₂]·2CH₂Cl₂ ( 1 ), [Cu₂(µ‐Br)₂(1,2‐(PPh₂)₂‐1,2‐C₂B₁₀H₁₀)₂]·2THF ( 2 ) and {Cu₂(µ‐I)₂[1,2‐(PPh₂)₂‐1,2‐C₂B₁₀H₁₀]₂} ( 3 ) have been synthesized by the reactions of CuX (X = Cl, Br and I) with the closo ligand 1,2‐(PPh₂)₂‐1,2‐C₂B₁₀H₁₀. All these complexes were characterized by elemental analysis, FT‐IR, ¹H and ¹³C NMR spectroscopy and X‐ray structure determination. Single crystal X‐ray structure determinations show that every complex contained di‐µ‐X‐bridged structure involving a crossed parallelogram plane formed by two Cu atoms and two X atoms (X = Cl, Br, I). The geometry at the Cu atom was a distorted tetrahedron, in which two positions were occupied by two P atoms of the PPh₂ groups connected to the two C atoms of carborane (Cc), and the other two resulted from two X atoms which bridged the other Cu atom at the same time. To the best of our knowledge, this is the first example of copper(I) complexes with 1,2‐diphenylphosphino‐1,2‐dicarba‐closo‐dodecaborane as ligand characterized by X‐ray diffraction. The catalytic property of the complex 3 for the amination of iodobenzene with aniline was also investigated. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis,structural characterization and luminescence properties of 1‐carboxymethyl‐3‐ethylimidazolium chloride

A microcrystalline carboxyl‐functionalized imidazolium chloride, namely 1‐carboxymethyl‐3‐ethylimidazolium chloride, C₇H₁₁N₂O₂⁺·Cl⁻, has been synthesized and characterized by elemental analysis, attenuated total reflectance Fourier transform IR spectroscopy (ATR‐FT‐IR), single‐crystal X‐ray diffraction, thermal analysis (TGA/DSC), and photoluminescence spectroscopy. In the crystal structure, cations and anions are linked by C—H…Cl and C—H…O hydrogen bonds to create a helix along the [010] direction. Adjacent helical chains are further interconnected through O—H…Cl and C—H…O hydrogen bonds to form a (10) layer. Finally, neighboring layers are joined together via C—H…Cl contacts to generate a three‐dimensional supramolecular architecture. Thermal analyses reveal that the compound melts at 449.7 K and is stable up to 560.0 K under a dynamic air atmosphere. Photoluminescence measurements show that the compound exhibits a blue fluorescence and a green phosphorescence associated with spin‐allowed (¹π←¹π*) and spin‐forbidden (¹π←³π*) transitions, respectively. The average luminescence lifetime was determined to be 1.40 ns for the short‐lived (¹π←¹π*) transition and 105 ms for the long‐lived (¹π←³π*) transition.     

Synthesis and characterization of new heterocyclic derivatives by oxidation of 1‐amino‐2‐methylindoline

1‐Amino‐2‐methylindoline is a precursor used in the synthesis of antihypertension drugs. It reacts with monochloramine to lead to the formation of 1‐amino‐2‐methylindole and azo(2‐methyl)indoline. These new products have been isolated and characterized by microanalysis, uv, gc/ms, ir, and ¹H/¹³C nmr. The reaction leads to the transient formation of an indolic aminonitrene. 1‐Amino‐2‐methylindole formation proceeds in strongly alkaline medium by rearrangement of a diaziridine intermediate. In neutral or slightly alkaline medium, one obtains a precipitate of tetrazene type (‐N‐N=N‐N‐), the azo(2‐methyl)indoline. The study of the thermochemical properties shows that tetrazene decomposes towards 150 °C to give the 1,1′‐bi(2‐methyl)indoline. The stability of the starting reagents and products was the subject of a systematic investigation. A reaction mechanism is proposed.     

Synthesis of new 1,2‐dihydrophthalazines

New 6‐chloro‐ and 6,7‐dichloro‐4‐(4‐aminophenyl)‐2‐(N‐alkylcarbamoyl)‐1,2‐dihydrophthalazines ( 12,18 ) were synthesized starting from 6‐chloro‐ and 6,7‐dichloro‐4‐(4‐nitrophenyl)phthalazine ( 8 ). Routes to 1‐unsubstituted ( 12 ) and 1‐methyl ( 18 ) derivatives are different. Key intermediates 8 were prepared from 4‐chloro‐ and 3,4‐dichlorotoluene via ortho‐formylbenzophenone derivatives 7 .     

Synthesis and characterization of oxime‐bearing hexakis(2‐formylphenoxy)‐phosphazene and its derivatives

Hexakis(2‐formylphenoxy)cyclotri‐phosphazene ( 2 ) was obtained from the reaction of hexachlorocylotriphosphazene ( 1 ) with 2‐hydroxy‐benzaldehyde. Hexakis(2‐[(hydroxyimino)methyl]‐phenoxy)cyclotriphosphazene (3) was synthesized from the reaction of 2 with hydroxlaminehydrochloride in pyridine. Hexasubstituted compounds 4, 5, 6, 8, 9 , and 10 were obtained from the reactions of 3 with methyl iodide, ethyl bromide, allyl bromide, propanoyl chloride, benzoyl chloride, and 4‐methoxybenzoyl chloride, respectively. Disubstituted product 7 was obtained from the reaction of 3 with chloroacetyl chloride. Pure and defined products could not be obtained from the reaction of 3 with acetyl chloride, benzyl chloride, and 2‐chlorobenzoyl chloride. The compounds were characterized by elemental analysis and IR, ¹H, ¹³C, and ³¹P NMR spectroscopy. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:791–797, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20350     

Synthesis,characterization and biological activity of some 1,2,4‐triazine derivatives

4‐Amino‐6‐methyl‐3‐(2H)‐thioxo‐5‐(4H)‐oxo‐1,2,4‐triazine ( 1 ) was condensed with 2‐methyl (or phenyl)‐4H‐3,1‐benzoxazin‐4‐one ( 5a,b ) in boiling acetic acid to give compounds 8‐11 . Reacting 1 with chloroacetyl chloride afforded the corresponding chloroacetamido and triazinothiadiazine derivatives 12 and 13 . Condensing 2 with succinic anhydride and/or phthalic anhydride yielded compounds 14 and 15 . Benzoylation of 4‐amino‐6‐methyl‐3‐(2H)‐thioxo‐5‐(4H)‐oxo‐2‐(2,3,4,5‐tetra‐O‐acetyl‐α‐D‐glucopyra‐nosyl)‐1,2,4‐triazine ( 19 ) afforded the corresponding 4‐N,N‐dibenzoyl derivative 20 . Deblocking of the N‐2 glycoside 21 and the S‐glycoside 22 by methanolic ammonia gave compounds 23 and 24 . Acetylation of 4‐amino glycoside 25a afforded the corresponding 4‐mono‐ and 4‐diacetyl derivatives 26 and 27 . Deamination of 25a,b yielded compounds 28a,b . Methylation of compound 28b afforded the corresponding N4‐ and S‐methyl derivatives 29 and 30 .     

Synthesis of 2‐phosphoro‐1,2‐thiazetidine 1,1‐dioxide

The reactions of phosphorochloridites 5a–c with an equimolar amount of 1,2‐thiazetidine 1,1‐dioxide (2) or L(−)‐3‐carboethoxy‐1,2‐thiazetidine 1,1‐dioxide (7) in the presence of triethylamine, affords the N‐phosphitylated β‐sultams 6a–b and L(−)‐8a,c. Their oxidation by addition of oxygen, sulfur, or selenium results in formation of stable organophosphorus β‐sultams 10a–b, L(−)‐11a,c, 12a, 13a, L(−)‐14c, and L(−)‐15c. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 61–67, 1999     

Synthesis and characterization of indeno[1,2‐b]fluorene‐based white light‐emitting copolymer

An indenofluorene‐based copolymer containing blue‐, green‐, and red light‐emitting moieties was synthesized by Suzuki polymerization and examined for application in white organic light‐emitting diodes (WOLEDs). Tetraoctylindenofluorene (IF), 2,1,3‐benzothiadiazole (BT), and 4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole (DBT) derivatives were used as the blue‐, green‐, and red‐light emitting structures, respectively. The number‐average molecular weight of the polymer was determined to be 25,900 g/mol with a polydispersity index of 2.02. The polymer was thermally stable (T_d = ～398 °C) and quite soluble in common organic solvents, forming an optical‐quality film by spin casting. The EL characteristics were fine‐tuned from the single copolymer through incomplete fluorescence energy transfer by adjusting the composition of the red/green/blue units in the copolymer. The EL device using the indenofluorene‐based copolymer containing 0.01 mol % BT and 0.02 mol % DBT units ( PIF‐BT01‐DBT02 ) showed a maximum brightness of 4088 cd/m² at 8 V and a maximum current efficiency of 0.36 cd/A with Commission Internationale de L'Eclairage (CIE) coordinates of (0.34, 0.32). The EL emission of PIF‐BT01‐DBT02 was stable with respect to changes in voltage. The color emitted was dependent on the thickness of the active polymer layer; layer (～60 nm) too thin was unsuitable for realizing WOLED via energy transfer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3467–3479, 2009     

Fatty acid hydrazides in heterocyclic synthesis: Synthesis of 1,2‐diazepine and pyridazine derivatives

1,2‐Diazepinone derivatives 6a–d, 8a,b, and 10a–c were synthesized from the reaction of olefines carrying EWG as ethoxymethylene malononitrile, ethoxymethylene cyanoacetate, and tetracyanoethylene with 1a–f respectively. Also, 5‐alkyl‐6‐oxotetrahydropyridazine‐4,4‐dicarboxylate derivatives 12a–c were afforded via the reaction of 1d–f with diethyl ethoxymethylene malonate. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:259–264, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20294