Meglumine sulfate-catalyzed one-pot green synthesis and antioxidant activity of α-aminophosphonates

A green and efficient synthetic protocol has been developed for the synthesis of a new series of substituted diethyl(((2-methoxy-5-(trifluoromethyl)phenyl)amino)(phenyl)methyl)phosphonates via a one-pot three-component reaction of 2-methoxy-5-trifluoromethyl aniline with various aromatic-substituted aldehydes and diethyl phosphite using meglumine sulfate as an eco-friendly catalyst at room temperature under solvent-free conditions. The merits of this method are high product yield, short reaction time, easy workup, and purification. All the synthesized compounds were evaluated for the antioxidant activity by DPPH, NO, and H₂O₂ methods using ascorbic acid as a standard. The compounds 4a and 4g showed the highest antioxidant activity than that of the standard ascorbic acid.     

Synthesis of Some 4‐Quinolinyl Pyridines and their Antimicrobial and Docking Studies

A series of some substituted diethyl 4‐(2‐chloroquinolin‐3‐yl)‐2,6‐dimethylpyridine‐3,5‐dicarboxylates has been synthesized from substituted diethyl4‐(2‐chloroquinolin‐3‐yl)‐1,4‐dihydro‐2,6‐dimethylpyridine‐3,5‐dicarboxylates (1,4‐DHPs) by treating the latter with SiO₂–HNO₃ which proved to be a better oxidant in terms of product yield, reaction time, and cost. Further, these compounds were screened for their antimicrobial activity. All the diethyl 4‐(2‐chloroquinolin‐3‐yl)‐2,6‐dimethylpyridine‐3,5‐dicarboxylates exhibited more potent activities than the corresponding 1,4‐DHPs. Further, docking simulation of the most active and least active compounds 3e and 2e into Escherichia coli topoisomerase II DNA Gyrase B was also performed.     

New class of diethyl substituted phosphoramidimidates and phosphonimidates: synthesis,spectral characterization and antimicrobial activity

Abstract

A series of new class of diethyl N-2-hydroxyethyl-N'-substituted phosphoramidimidates 6(a–e) and diethyl P-morpholino-N-substituted phosphonimidates 6(f–j) was synthesized. The precursor intermediates, diethyl substituted phosphoramidites 3(a–b) were prepared initially by a reaction of various amines 1(a–b) and diethyl phosphorochloridite (2) and then they were treated by in situ with aromatic/alkyl azides through Staudinger reaction to accomplish title products. Structures of all the synthesized compounds were characterized by spectroscopic data such as IR, NMR (¹H, 13C, ³¹P), mass, and elemental analyses. The synthesized compounds were screened for their in vitro antimicrobial activity to understand their biological potency. The biological screening results disclosed that compounds 6b, 6c, 6e, 6g, 6h and 6j having potent antimicrobial activity against all the tested pathogens.     

In(OTf)3 catalysed simple one-pot synthesis of α-amino phosphonates

A new efficient one-pot synthesis of α-amino phosphonates derived from nitro substituted anilines, aldehydes and diethyl phosphite has been carried out by employing 5 mol% of In(OTf)₃. The method is equally effective for the generation of α-amino phosphonates from various carbonyl compounds and other amines.     

C,N‐chelated organotin(IV) compounds as catalysts for transesterification and derivatization of dialkyl carbonates

The potential catalytic activity of selected C,N‐chelated organotin(IV) compounds (e.g. halides and trifluoroacetates) for derivatization of both dimethyl carbonate (DMC) and diethyl carbonate (DEC) was investigated. Some tri‐, di‐ and monoorganotin(IV) species (L^CN(n‐Bu)₂SnCl (1), L^CN(n‐Bu)₂SnCl.HCl (1a), L^CN(n‐Bu)₂SnI (2), L^CNPh₂SnCl (3), L^CNPh₂SnI (4), L^CN(n‐Bu)SnCl₂ (5), L^CNSnBr₃ (6) and [L^CNSn(OC(O)CF₃)]₂(μ‐O)(μ‐OC(O)CF₃)₂ (7)) bearing the L^CN moiety (L^CN = 2‐(N,N‐dimethylaminomethyl)phenyl‐) were assessed as catalysts for reactions of both DMC and DEC with various substituted anilines. The catalytic activities of 4 and 7 for derivatization of DMC with p‐substituted phenols were studied for comparison with the standard base K₂CO₃/Silcarbon K835 catalyst (catalyst 8). The composition of resulting reaction mixtures was monitored by multinuclear NMR spectroscopy, GC and GC‐MS techniques. In general, catalysts 1, 3 and 7 exhibited the highest catalytic activity for all reactions studied, while some of them yielded selectively carbonates, carbamates, lactam or substituted urea. Copyright © 2012 John Wiley & Sons, Ltd.     

Nonclassical urea oligomers. I. Selective reactivity of 1-(N-substituted-carbamyl)aziridine for ring-transformation reactions and ring-opening polymerization

The reaction course of 1-(N-phenyl-carbamyl)aziridine with NaI was found to be highly sensitive to the nature of solvent used; e.g., acetone preferentially gives 1-phenyl-2-imidazolidinone, whereas dimethylformamide (DMF) gives 2-anilino-2-oxazoline. Nuclear magnetic resonance (NMR) study of the solvent effect revealed the relation between the site in the aziridine compound, with which the solvents interact, and the reaction products. From the results obtained by these ring-transformation studies, the use of diethyl sulfate, which is expected to solvate simultaneously at the carbonyl oxygen and the carbamyl–nitrogen atoms, resulted in polymerization of the monomer selectively to the oligomer of type—[CH₂CH₂N(CONHPh)]_n—. The diethyl sulfate was shown to play dual roles as a solvating reagent and an initiator. The oligomer obtained includes relatively definite amount (one molecule per ca. four monomer units) of diethyl sulfate in the “washed” state. The absorbed diethyl sulfate can be removed by treating with aqueous NaOH solution or Amberlite-400 column elution without altering the chemical constitution of the backbone in the polymer. Application of the polymerization procedure to several N-alkyl substituted monomers resulted in oligomers of a similar type. The difference in the monomer reactivity depending on the nature of the substituent groups can be due mainly to steric factors.     

Efficient Access to Substituted Silafluorenes by Nickel‐Catalyzed Reactions of Biphenylenes with Et2SiH2

The reaction of biphenylene ( 1 ) with Et₂SiH₂ in the presence of [Ni(PPhMe₂)₄] results in the formation of a mixture of 2‐diethylhydrosilylbiphenyl [ 2 (Et₂HSi)] and 9,9,‐diethyl‐9‐silafluorene ( 3 ). Silafluorene 3 was isolated in 37.5 % and 2 (Et₂HSi) in 36.9 % yield. The underlying reaction mechanism was elucidated by DFT calculations. 4‐Methyl‐9,9‐diethyl‐9‐silafluorene ( 7 ) was obtained selectively from the [Ni(PPhMe₂)₄]‐catalyzed reaction of Et₂SiH₂ and 1‐methylbiphenylene. By contrast, no selectivity could be found in the Ni‐catalyzed reaction between Et₂SiH₂ and the biphenylene derivative that bears tBu substituents in the 2‐ and 7‐positions. Therefore, two pairs of isomers of tBu‐substituted silafluorenes and of the related diethylhydrosilylbiphenyls were formed in this reaction. However, a subsequent dehydrogenation of the diethylhydrosilylbiphenyls with Wilkinson’s catalyst yielded a mixture of 2,7‐di‐tert‐butyl‐9,9‐diethyl‐9‐silafluorene ( 8 ) and 3,6‐di‐tert‐butyl‐9,9‐diethyl‐9‐silafluorene ( 9 ). Silafluorenes 8 and 9 were separated by column chromatography.     

Utilisation en synthese du cation iminium genere in situ par oxydation electrochimique d'amines tertiaires

The electrochemical oxidation in acetonitrile of aliphatic amines (ACH₃) in presence of a non-nucleophilic base (2,4,6-collidine) and of compounds containing weakly-activated hydrogens (RH) such as diethyl phosphonate and diethyl malonate gives the substituted derivatives ACH₂R. These compounds result from the addition of the anion R^? to the iminium cation ACH₂⁺. Such a reaction is obtained with tribenzylamine and N,N-dimethyl-p-toluidine. Moreover (CH₃)₂NCH₂-CH(CO₂C₂H₅)₂ is deaminated and gives by successive Michael reactions other substituted malonates which also react with the iminium cation (CH₃)2N⁺CH₂.     

Synthesis and Properties of Brominated 6,6'-Dimethyl-[2,2'-bi-1H-indene]-3,3'-diethyl-3,3'-dihydroxy-1,1 '-diones

Photochromic 6‐bromomethyl‐6′‐methyl‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 2 ), 6,6′‐ bis(bromomethyl)‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 3 ) and 6,6′‐bis(dibromomethyl)‐[2,2′‐ bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 4 ) have been synthesized from 6,6′‐dimethyl‐[2,2′‐bi‐1H‐ indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 1 ). The single crystal of 4 was obtained and its crystal structure was analyzed. The results indicate that in crystal 4 , molecular arrangement is defective tightness compared with its precursor 1 . Besides, UV‐Vis absorption spectra in CH₂Cl₂ solution, photochromic and photomagnetic properties in solid state of 2 , 3 and 4 were also investigated. The results demonstrate that when the hydrogen atoms in the methyl group on the benzene rings of biindenylidenedione were substituted by bromines, its properties could be affected considerably.     

About the Mechanism of the Reaction Cuprous Dialkyl Thiophosphates with the Alkynyl Halides

Abstract

Cuprous dialkyl thiophosphates are convenient reagents for the synthesis of the organophosphorus compounds with the α-acetylenic bond in the alkthiolic radical, and for steric hindered S-propargyl thiophosphates. X-ray investigation established that the crystal is constructed of the tetramer molecules Cu₄[(EtO)₂PSO]₄.¹ The tetramer is a tetrahedral claster of Cu atoms coordinated with four three-dentant chelate-bridged diethyl thiophosphate ligands. Firmly coordinated diethyl thiophosphate ligand in the copper complex does not possess nucleophilic properties and does not react with alkyl bromide. EPR spectroscopy established that the ethynylation of cuprous dialkyl thiophosphate by the substituted ethynyl bromides proceeds via the paramagnetic cupric complex formation. The latter, being unstable under usual conditions, decomposes with the formation of substituted S-ethynyl thiophosphates and CuBr.² Sterically hindered halides of the propargyl type are not liable to Sn2 reaction with the potassium salts of dialkyl thiophosphoric acids, but they readily react with the cuprous salts of these acids yielding S-propargyl thiophosphates. This process is a redox one and it proceeds via the paramagnetic cupric complex formation.     

The Synthesis and Reactivity of Alkylaminomethylene-Diphosphonates

Abstract

A accessible method for the synthesis of various alkylaminomethylenediphos-phonates is presented. The performed Vilsmeier reagents 2 (RCONR1R²/POCl₃) react with diethyl phosphite 1 to give the products 1 in good yield.     

A Simple Way of Synthesis of Bisethylthiopolymethylene Sulfides EtS(CH2S)nEt

Two methods of synthesis of bisethylthiopolymethylene sulfides RS(CH₂S) _n R (R = Et, n 1) are developed. Both approaches are based on the reductive cleavage of the S-S bonds in diethyl polysulfides or a mixture of diethyl polysulfides with elementary sulfur by the system: hydrazine hydrate-base. Subsequent alkylation of the formed thiolate anions with dichloromethane leads to the formation of mixtures of oligomeric bisethylthiopolymethylene sulfides with a predominance of compounds with n = 1, 2.     

A facile synthesis of 3‐Substituted 5‐Oxo‐1,2,4‐thiadiazoles from amidoximes

The reaction of amidoximes 1 with 1,1′‐thiocarbonyldiimidazole (TCDI) followed by treatment with silica gel or boron trifluoride diethyl etherate (BF₃·OEt₂) provided 3‐substituted 4,5‐dihydro‐5‐oxo‐1,2,4‐thiadiazoles 2 in moderate yields. The Lewis acids are considered to promote the rearrangement of the thioxocarbamate intermediates 5 to the thiol carbarn ate intermediates 7 , which cyclize to afford 4,5‐dihydro‐5‐oxo‐1,2,4‐thiadiazoles 2 .     

CeCl3·7H2O Catalyzed,Microwave-Assisted High-Yield Synthesis of α-Aminophosphonates and their Biological Studies

Abstract

A new class of diethyl(3,5-dibromo-4-hydroxyphenylamino) (substituted phenyl/heterocyclic) methylphosphonates 4(a–j) has been synthesized by one-pot three component simultaneous reaction (Kabachnik–Fields) of 4-amino-2,6-dibromophenol 1, substituted heterocyclic/phenyl aldehydes 2(a–j), and diethylphosphite 3 using a Lewis acid catalyst, CeCl₃·7H₂O (5 mol%) under microwave irradiation as well as conventional conditions. It was observed that microwave irradiation method is more facile, efficient, and advantageous with respect to reaction time and yields. The structures of all the synthesized compounds were supported by analyzing IR, ¹H/¹³C/³¹P NMR, and mass spectral data. The synthesized compounds were screened for their in vitro antimicrobial and antioxidant activities.     

Highly active Pd-Fe/α-Al_2O_3 catalyst with the bayberry tannin as chelating promoter for CO oxidative coupling to diethyl oxalate

A novel Pd-Fe/α-Al_2O_3 catalyst was synthesized by incipient-wetness impregnation method with bayberry tannin as chelating promoter and commercial hollow column Raschig ring a-Al_2O_3 as support for the synthesis of diethyl oxalate from CO and ethyl nitrite.A variety of characterization techniques including N_2 physical adsorption,optical microscopy,scanning electron microscopy and energy dispersive system(SEM-EDS),inductively coupled plasma optical emission spectroscopy(ICP-OES),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),were employed to explore the relationship between the physicochemical properties and activity of catalysts.It indicated that a large number of phenolic hydroxyl groups in bayberry tannin can efficiently anchor the active component Pd,reduce the particle size and make the active Pd as a multi-ring distribution on the commercial a-Al_2O_3 suppo rt,which we re beneficial to improve the catalytic activity for the production of diethyl oxalate from CO and ethyl nitrite.0.3 wts Pd-Fe/α-Al_2O_3 showed excelle nt catalytic activity and selectivity in a continuous flow,fixed-bed reactor with the loading amount of 10 mL catalysts,Under the mild reaction conditions,the space-time yield of diethyl oxalate was 978 g L ~1 h ~1 and CO conversion was 44% with the selectivity to diethyl oxalate of 95.5%.     

Formation of Chromene Analogs of Homophthalates: Investigation of Condensation Products Derived from 2-Hydroxybenzaldehydes and Diethyl 2-Pentenedicarboxylates

Condensation of substituted 2-hydroxybenzaldehyde derivatives (1a-1) with diethyl 2-pentenedicarboxylate (2) in the presence of piperidine gave coumarin and / or chromene derivatives. Attempted reaction of 4-N,N-diethylamino-2-hydroxybenzaldehyde (1a) and 2-hydroxy-3-nitrobenzaldehyde (1i) with diethyl 3-phenyl-2-pentenedicarboxylate (5) led to formation of no coumarin or chromene derivative.     

Reaction of sterically congested NHC–Zn(CH2CH3)2 with substituted phenols leading to zincate complexes

We report the reaction of a sterically congested NHC–Zn(CH₂CH₃)₂ Lewis adduct (1) prepared through reaction of an equimolar ratio of 1,3-di-tert-butylimidazol-2-ylidene and diethyl zinc, with various substituted phenols (4-tert-butyl-phenol, 2,6-di-tert-butyl-4-methyl phenol, and 1-bromo-4,6-di-tert-butyl phenol). The NHC–Zn dative bond was cleaved in each of the reactions with the substituted phenols to afford the corresponding ionic complexes of imidazolium cation and aryloxo-zincate, [{(4-CMe₃C₆H₄O)₂Zn(μ-OC₆H₄-4-CMe₃)}₂{(1,3-(CMe₃)_2-ImCH}₂] (2), [{(2,6-(CMe₃)₂-4-Me-C₆H₃O)₂}Zn{(1,3-(CMe₃)_2-ImCH}] (3), and [{(1-Br-3,5-(CMe₃)₂C₆H₂O)₂}_2-Zn{(1,3-(CMe₃)_2-ImCH}] (4), where 1,3-(CMe₃)_2-ImCH) is imidazolium carbocation. The molecular structures of 1–4 were established by X-ray diffraction analyses and from the solid-state structures of 2–4, it was confirmed that, in all the compounds, zinc ions are coordinated through substituted phenolate groups.     

Efficient halogenation of unsaturated organoaluminum compounds with sulfonyl halides

Alkenylalumanes prepared by carbo-or cycloalumination of substituted acetylenes reacted with an equivalent amount of sulfonyl halide (MsCl, TsCl, PhSO₂Cl, MsBr) in methylene chloride or hexane at room temperature to produce alkenyl halides in high yields. Electron-donor solvents such as diethyl ether or tetrahydrofuran inhibited the halogenation process. β-Substituted vinylalumanes generated by hydroalumination of substituted acetylenes failed to react with sulfonyl halides.     

Synthesis and antimicrobial studies of new pyridine derivatives

2-(p-Acetylaminobenzenesulfonylamido)-substituted benzothiazoles were prepared from 2-amino-substituted benzothiazoles and p-acetamidobenzenesulfonyl chloride using a mixture of pyridine and Ac₂O, which formed an electrophilic N-acetyl- pyridinium complex facilitating condensation to give the desired products by removal of HCl. 2-[4-(Substituted benzothiazol-2-yl)aminosulfonylanilino]pyridine-3-carboxylic acids (synthesized from 2-chloropyridine-3-carboxylic acid and the corresponding substituted 2-(p-aminobenzenesulfonylamido)benzothiazole in 2-ethoxyethanol using Cu-powder and K₂CO₃) were then converted to acid chlorides, which on further reaction with piperazine and 4-methoxyphenylpiperazine yielded the corresponding 2-[4-(substituted benzothiazol-2-yl)amino-sulfonyl]anilino-3-(piperazinocarbonyl) pyridine and 2-[4-(substituted benzothiazol-2-yl)amino-sulfonyl]anilino-3-[(4-methoxyphenyl)piperazin-1-yl-carbonyl]pyridine. The structures of the new compounds have been established on the basis of their elemental analyses as well as IR, ¹H NMR, and mass-spectral data. All the compounds have been screened for antimicrobial activity and found to possess considerable antibacterial activity.     

联二噻吩稠合的近红外BODIPY染料的合成与光谱性质

以叠氮乙酸乙酯和联二噻吩甲醛为原料,合成了联二噻吩并吡咯单体,之后在酸催化下与4-N,N-二甲基氨基苯甲醛缩合并与三氟化硼配位,得到一个新型的BODIPY染料SY。采用~1HNMR、质谱以及元素分析对其结构进行了表征。化合物SY在二氯甲烷中的最大吸收和发射波长分别为654和689nm;采用荧光光谱滴定方法研究了它对pH值的响应,酸性条件下N,N-二甲基苯氨基团发生质子化,抑制了光诱导电子转移对BODIPY母体的荧光淬灭,其溶液的荧光显著增强,染料SY可以作为近红外的pH值荧光探针。