The 1H NMR spectra of p-substituted phenyl 2-chloro-2-fluoroethyl sulphides

The 60 MHz ¹H NMR spectra of p-substituted phenyl 2-chloro-2-fluoroethyl sulphides have shown characteristic patterns; in the ABC portion of an ABCX spin system (X = ¹⁹F) of the compounds, one of the subspectra shows an ABC pattern and the other apparently an AB₂ pattern. These spectral patterns have been analysed and the ¹H NMR data obtained are discussed briefly.     

Synthesis and Antimicrobial Studies of Organophosphates Derived From 2-(2″-Hydroxynaphthyl)Benzoxazole

Abstract

A series of biologically active phenoxy derivatives of 2-substituted benzoxazole organophosphates have been synthesized by the reaction of O-(naphthyl benzoxazolyl-2-) phosphorodichloridate/phosphorodichloridothioate with phenol/4-chlorophenol/4-nitroph- enol in 1:1 and 1:2 molar ratios. These compounds have been characterized on the basis of elemental analysis, IR, ¹H NMR, ³¹P NMR, and mass spectral studies. The antibacterial activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (?ve). The antifungal activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. All compounds were found to have significant antibacterial and antifungal activity.     

Synthesis and Antimicrobial Activities of Novel Series of 1-((4-Methyl-2-Substituted Thiazol-5-yl)Methyleneam INO)-2-Substituted Isothiourea Derivatives

A novel series of 1-((4-methyl-2-substituted thiazol-5-yl)methyleneamino)-2-substituted isothiourea derivatives was synthesized by alkylation of (Z/E)-1-((4-methyl-2-substituted thiazol-5-yl)methylene)thiosemicarbazide with alkylhalide in acetone. All the newly synthesized compounds were characterized by spectral (IR, ¹H NMR, ¹³C NMR, and mass spectrometry) methods. The newly synthesized compounds were screened for in vitro antimicrobial activity. Most of the compounds show moderate to excellent antimicrobial activity.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables.]     

New unsymmetrical difluoroaromatic compounds and estimation of their reactivities in nucleophilic substitution

A series of previously unknown unsymmetrical difluoroaromatic compounds, viz., p-fluorobenzoylphenyl(p-fluorophenyl)-substituted imidazoles, pyrazines, and quinoxalines, were synthesized according to multistep procedures with the use of chloral as the key compound. The reactivities of the resulting difluoroaromatic compounds were estimated based on ¹⁹F and ¹³C NMR spectral data and the results of quantum-chemical calculations. The calculated charge densities on the C_ipso atoms correlate linearly with the experimental chemical shifts in the ¹⁹F and ¹³C NMR spectra. Difluoroaromatic compounds, which are characterized by _F > –110 and _C > 163 and by the charge density on the C_ipso atom higher than 0.08 e, are sufficiently activated to be used for the preparation of high-molecular-weight polyethers.     

Green chemistry approach to the synthesis of 3-substituted-quinazolin-4(3H)-ones and 2-methyl-3-substituted-quinazolin-4(3H)-ones and biological evaluation

ABSTRACT

A synthesis of two series of 3-substituted quinazolinones was performed utilizing a green chemistry approach, deep eutectic solvents and microwaves, namely. 2-Methyl-3-substituted-quinazolin-4(3H)-one derivatives were synthesized in a two-step reaction, using choline chloride:urea deep eutectic solvent (DES). 3-Substituted-quinazolin-4(3H)-ones were synthesized in one-pot one-step reaction of anthranilic acid, amines and orthoester in a microwave reactor. For the synthesis of 2-methyl-3-substituted-quinazolin-4(3H)-ones, first conventional synthesis of benzoxazinone, as an intermediate, was performed. Further, benzoxazinone in reaction with corresponding amines, in choline choline:urea deep eutectic solvent, furnished desired compounds. These procedures are based on green principles with the aim of developing synthetic routes for the potential antitumor agents. All compounds were characterized by LC/MS, ¹H NMR and ¹³C NMR spectral techniques. Compound 1 bearing trifluoromethoxyphenyl group showed promising activity against HuT-78 cell line with IC₅₀ of 51.4?±?5.1?µM.     

Studies on organophosphorus compounds: XV. A new method for the synthesis of α-amino-substituted benzylphosphonic acids

A new synthetic method for the preparation of α-amino-substituted benzylphosphonic acids with moderate to good yields was developed by the following sequence of reactions. Diethyl phosphoramide was reacted with substituted benzaldehyde and triphenyl phosphite in the presence of catalytic amount of BF₃·Et₂O. Diphenyl α-(N-phosphorylamino)-substituted benzylphosphonates ( 1 ) thus obtained was then treated with hydrogen bromide in acetic acid to remove selectively the amino-protecting group with the formation of diphenyl α-amino-substituted benzylphosphonates ( 2 ), a key intermediate in phosphorus peptide synthesis, which was then successively hydrolyzed with hydrobromic acid to give corresponding hydrobromide of α-amino-substituted benzylphosphonates with excellent yields. The free aminophosphonic acid ( 3 ) was obatined from the latter by treatment with propylene oxide. ³¹P NMR studies demonstrated that a linear relationship exists in plotting δ versus δ constants of nuclear substituent in 1 series. The p-substituted compounds give, as a rule, higher value in ³¹P NMR spectra than those from meta- and ortho-substituents.     

Spectral and electrochemical behavior of 1-[(NO2, COOH)-substituted phenyl]-3,5-diphenylformazans

Abstract  

1-[(NO₂, COOH)-substituted phenyl]-3,5-diphenylformazans were synthesized. The compounds were characterized by infrared (IR), ultraviolet–visible (UV–vis), ¹H nuclear magnetic resonance (NMR), ¹³C NMR spectra, elemental analysis, and cyclic voltammetry. From the UV–vis spectra of substituted formazans it was seen that λ _max values were shorter than the λ _max value of unsubstituted formazan. It was observed that the shift values were dependent on the type and position of the substituents. A correlation between Hammett substituent coefficients and λ _max values was obtained. The oxidation peak potentials of substituted formazans were found more anodic than that of unsubstituted formazan. The oxidation mechanism was a single step for the NO₂-substituted formazans, and two steps for COOH-substituted formazans.     

1H- und 13C-NMR-Untersuchungen zur Struktur N-substituierter Tetrazole—Die Strukturen des N-Methoxycarbonyl-, N-Acetyl- und N-(Tri-n-butylstannyl)-tetrazols sowie Substituenteneffekte auf δ13C und 1J(CH)

The ¹H and ¹³C NMR spectra of several isomeric N-substituted tetrazoles have been investigated. ¹³C NMR is shown to be more useful for distinguishing between structural isomers of N-substituted tetrazoles except for those carrying electropositive substituents like SnBu₃. Correlations of δC-5 (inverse) and ¹J(C-5,H) with s?₁ found for 1-substituted tetrazole allowed the identification of the N SnBu₃ derivative as 1-(tri-n-butylstannyl)tetrazole. The phenyl carbon chemical shift difference ΔC′ = δC-3′-δC-2′ is insignificant for structure elucidation and conformational studies of N-substituted 5-phenyltetrazoles; ΔH′ from ¹H NMR spectra seems to be more useful.     

Design,synthesis and biological evaluation of novel N1,N8-bis(((4-((5-aryl-1,3,4-oxadiazol-2-yl)methoxy)phenyl)amino)oxy)-1-naphthamide derivatives

A new series of 1,8-bis(4-((5-phenyl-1,3,4-oxadiazol-2-yl) methoxy)-substituted aryl) naphthalene-1,8-dicarboxamide derivatives (6a–j) were synthesized in the presence of POCl₃ and obtained good yields. All the synthesized novel compounds were characterized by IR, ¹H NMR, ¹³C NMR, HRMS spectroscopic data and elemental analysis. All the synthesized compounds evaluated for their antibacterial and antifungal activities. The antibacterial activity screened against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli and used standard reference drug ciprofloxacin. The antifungal activity screened against two pathogenic fungal strains Aspergillus niger and Candida albicans used a reference standard drug Voriconazole. All these compounds (6a–j) demonstrate good antibacterial and antifungal activity. Among them, compounds 6h and 6c show highest antibacterial and antifungal activity.     

Etude par Résonance Magnétique Nucléaire du 13C des chlorhydrates de-N-(phényl-1 cyclohexyl) piperidines.

The conformations of N-(1-phenylcyclohexyl)piperidinium chloride and some 4-substituted derivatives in H₂O and CDCl₃ were studied by means of ¹³C NMR. The results confirm the greater stability of compounds with equatorial piperidinium. Certain characteristics in the observed chemical shifts may be attributed to deformations of the cyclohexyl system, probably caused by the phenomenon of solvation.     

1H, 13C and 199Hg NMR Studies of the Complexation of HgCl2 by Imidazolidine-2-Thione and its Derivatives

Abstract

Mercury(II) complexes of imidazolidine-2-thione and its derivatives have been synthesized and their ¹H, ¹³C and ¹⁹⁹Hg NMR spectra measured. HgCl₂ forms L₂HgCl₂ type complexes (where L = imidazolidine-2-thione and its derivatives). The NH group of the ligand is shifted downfield by about +1.37 ppm in the ¹H NMR after complexation. The C-2 carbon in the ¹³C NMR is shifted by—6.50 ppm for mono N-substituted ligands, but by—5.30 ppm for N,N''-disubstituted ligands. The ¹⁹⁹Hg NMR resonance is shifted by about—60 ppm for N-substituted ligands, but—140 ppm shifts were observed for N',N'-disubstituted ligands.     

New azobenzene-based natural fatty acid liquid crystals with low melting point: synthesis,DFT calculations and binary mixtures

ABSTRACT

Three new groups of azobenzene liquid crystals named,4-[2-(4-substituted phenyl)diazenyl]phenyl hexdecanoate, 4-[2-(4-substituted phenyl)diazenyl]phenyl octadeca-9-enoate, and 4-[2-(4-substituted phenyl)diazenyl]phenyl octadeca-9,12-dienoate were prepared from naturally occurring fatty acids (palmitic, oleic and linoleic acids). All groups were investigated for their mesophase formation and thermal stability of pure compounds and their binary mixtures by differential scanning calorimetry (DSC), polarised light microscopy (PLM) and thermogravemetric analyses (TGA). Each group contains two compounds that differ from each other by the polar substituent X (CH₃O and Cl) with different number (n) of carbons in the fatty alkyl chains. Molecular structures of the prepared compounds were confirmed via FT-IR, ¹H NMR, C¹³ NMR and elemental analysis. Mesomorphic and thermal properties were investigated. Smectic A phase is the mesophase observed in all of the compounds prepared and their binary mixtures with low melting temperatures. Moreover, DFT calculations were discussed for the prepared compounds. The results revealed that the alkyl chain of the carboxylate part does not significantly affect on the energy difference of the FMOs as well as the thermodynamic parameters. However, the high electronegative Cl substituent has significant effect on the energy difference of the FMOs and decreases the dipole moments of the prepared compounds.     

N-取代苯甲酰基-N'-取代芳基硫脲的合成、晶体结构及生物活性

为了寻找新的高活性农药, 利用工业易得的三氟羧草醚及其中间体为起始原料, 设计合成了9个未见报道的N-取代苯甲酰基-N'-取代芳基硫脲化合物, 结构经IR, ¹H NMR, 元素分析确认. X射线衍射测定了化合物4b的晶体结构, 结果表明: 其分子属于三斜晶系, 空间群P-1, a＝0.51588(19) nm, b＝1.0766(4) nm, c＝2.0596(8) nm, α＝81.113(6)°, β＝89.702(6)°, γ＝78.131(6)°, V＝1.1056(7) nm³, D_c＝1.445 Mg/m³, Z＝2, F(000)＝492, μ＝0.319 mm^－1. 初步生物活性测试结果表明, 部分化合物具有较好的除草活性.     

Cinnamoylacetanilides and Their Metal Chelates

A new series of β-ketoanilides, in which the keto group attached to an olefinic linkage, have been synthesized by the reaction of acetoacetanilide with p-substituted benzaldehydes (4-methoxybenzaldehyde, 4-ethoxybenzaldehyde, 4-dimethylaminobenzaldehyde and 4-nitrobenzaldehyde) under specified conditions. The existence of these β-ketoanilides predominantly in the intramolecularly hydrogen bonded enol forms has been well demonstrated from their IR, ¹H NMR and mass spectral data. Details on the formation of [ML₂] complexes of these compounds with Ni(II), Cu(II) and Zn(II) and their nature of bonding were discussed on the basis of analytical, IR, ¹H NMR and mass spectral data.     

Electronic Structure of π Systems: XIX. Keto-Enol Tautomerism of Dihydrofurocoumarinones

Tautomeric transformations of 4-methyldihydrofuro[2,3-h]coumarin-9-one and its 8-substituted derivatives were studied by ¹H NMR, electronic absorption spectroscopy, and quantum chemistry. The ¹H NMR spectra of these compounds in CDCl₃ show that they exist in the ketone form, and in more polar sol- vents they can pass into the enol form. By electronic absorption spectroscopy it was established that the derivatives containing electron-acceptor substituents in the 8 position of the furanone ring undergo tautomeric transformations as the composition of the solvent is varied from 100% methanol to 100% CCl₄. At the same time, the derivatives with electron-donor substituents in the same position do not show any specific alterations in the absorption spectra with solvent. Analogous pattern was observed in the enolization of substituted di- hydrofurocoumarinones by acetylation: In presence of electron-donor substituents in the 8 position, no acetyla- tion occurred, while with the compounds containing electron-acceptor substituents, the corresponding 9-acet- oxy-4-methylangelicins were prepared in high yields. Calculations by the PPP/CI method of the electronic absorption spectra 4-methyldihydrofuro[2,3-h]coumarin-9-one showed that in polar solvents (methanol) it prefers the enol form. Data of spectral measurements were compared with results of semiempirical (MNDO, AM1, and PM3) and nonempirical quantum-chemical calculations (with 3-21G, 6-31G^*, and 31G^** basis sets).     

Synthesis of 4-amino-2,6-diaryl-5-cyanopyrimidines as antimicrobial agents

This article describes an efficient and facile synthesis of 11 2,4,6-trisubstituted 5-cyanopyrimidines starting from meta- and para-substituted 2-cyanocinnamonitriles and arylamidines. The synthesized heterocycles, 3a–k, were characterized by infrared (IR), ¹H NMR, ¹³C NMR, and mass spectral data. The probable mechanism of formation of the title compounds employing 2-cyanocinnamonitriles and arylamidines in the presence of a base was clarified. A preliminary screening of the antibacterial tests clearly showed that 4 out of 11 pyrimidines, 3a, 3e, 3f, and 3k, were effective against bacteria Staphyloccus aureus, Bacillus subtillis, and Pseudomonas aeruginosa. Further, the minimum inhibitory concentration (MIC) against the bacteria has been determined.     

SYNTHESIS AND BIOLOGICAL ACTIVITY OF N-AROYL-N′-SUBSTITUTED THIOUREA DERIVATIVES

A series of N-aroyl-N′-substituted thiourea derivatives have been prepared in good to excellent yields under the condition of solid-liquid phase transfer catalysis using polyethylene glycol-400(PEG-400) as the catalyst. The products have been characterized on the basis of analytical and spectral (IR and ¹H NMR) data. The promoting effects of some compounds on wheat growth have been tested preliminary.     

含苯并噻唑基乳糖基胍的合成

2,3,6,2',3',4',6'-七-O-乙酰基-β-乳糖基异硫氰酸酯(1)分别与2-氨基-4/6-取代苯并噻唑2a～2e反应, 制得糖基硫脲3a～3e, 将其在HgCl₂作用下与伯胺反应, 制得一系列新化合物N-烷基/芳基-N'-(4/6-取代-苯并噻唑-2-基)-N'-(2,3,6,2',3',4',6'-七-O-乙酰基-β-乳糖基)胍4～6. 然后, 在CH₃ONa/CH₃OH作用下, 脱乙酰基得含苯并噻唑基的乳糖基胍类化合物7～9. 所有新化合物的结构均经IR, ¹H NMR, MS谱和元素分析证实, 所得产物均为b-构型. 对代表性化合物的生物活性测试结果表明, 乳糖基胍类化合物对HIV-1蛋白酶、血管紧张素转化酶(ACE)的抑制活性较差.     

胍基木吡喃糖苷的合成及其抗HIV蛋白酶活性

2,3,4-三-O-乙酰基-b-D-木吡喃糖基异硫氰酸酯1与2-氨基-4/6-取代-苯并噻唑2a～2e反应, 生成糖基硫脲衍生物3a～3e, 再在伯胺存在下经氯化汞脱硫, 得到一系列新的胍基木吡喃糖苷类化合物4a～4e, 5a～5e, 6a～6e, 7a～7e, 所有新化合物的结构均经IR, ¹H NMR, MS谱和元素分析证实, 所得产物均为β-构型. 生物活性测试结果表明, 化合物4c, 5b, 6b～6d, 7b等对HIV-1蛋白酶表现出了较高的抑制活性.     

New isomeric N‐substituted hydrazones of 2‐, 3‐ and 4‐pyridinecarboxaldehydes and methyl‐3‐pyridylketone

Twelve compounds unknown in the literature N‐(E)‐2‐stilbenyloxymethylenecarbonyl substituted hydrazones of 2‐, 3‐ and 4‐pyridinecarboxaldehydes, as well as methyl‐3‐pyridylketone have been prepared. The stereochemical behavior of these compounds in dimethyl‐d₆ sulfoxide solution has been studied by ¹H NMR technique. The E geometrical isomers and cis/trans amide conformers have been found for N‐substituted hydrazones 1–12. EI induced mass spectral fragmentation of these compounds were also investigated. The data obtained create the basis for distinguishing isomers.