17O, 13C and 1H NMR and IR spectral study of crowded ketones: possible intramolecular C—H···O interactions

Unusual behaviour was observed in the study of the ¹⁷O, ¹³C and ¹H NMR and IR spectra of crowded (1‐adamantyl)alkyl ketones. As the size of the alkyl substituent is increased, abnormal upfield chemical shifts in the ¹³C NMR and downfield shifts in the ¹⁷O NMR of the carbonyl group, as well as downfield shifts in the ¹H NMR of the adamantyl γ'‐protons, are found. In the IR spectrum, the ν_C?O stretching frequencies of the ketones with bulky substituents show considerable red shifts. Correlation of the NMR shifts with the number of γ‐carbon atoms of the alkyl substituents and comparison with the IR results indicated that there is an intramolecular through‐space CH···O interaction in crowded ketones. This was supported by the results of ab initio calculations. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis and Pharmacological Evaluation of a Novel Series of 2‐((2‐Aryl thiazol‐4‐yl)methyl)‐5‐(alkyl/alkylnitrile thio)‐1,3,4‐oxadiazole Derivatives as Possible Antifungal Agents

In the present investigation, a novel series of 2‐[(2‐arylthiazol‐4‐yl)methyl]‐5‐(alkyl/alkylnitrile thio)‐1,3,4‐oxadiazole derivatives were synthesized by cyclo‐condensation of 2‐(2‐substituted thiazol‐4‐yl)aceto hydrazide with carbon disulfide followed by S‐alkylation with alkyl halide in dry acetone. All the newly synthesized compounds were characterized by spectral (IR, ¹H NMR, ¹³C NMR, mass, and elemental analysis) methods. The title compounds were screened for in vitro antifungal activity and most of the synthesized compounds show moderate to good antifungal activity.     

Survey Reactivity of Some Substituted Quinazolinones with Pentafluoro(chloro)pyridine

A new series of 4‐hetroaryl substituted quinazolines were designed and synthesized by the reaction of pentafluoro(chloro)pyridine and 2‐substituted quinazolinone. The aromatic nucleophilic substitution of pentafluoro(chloro)pyridine with quinazolinone occurs at the 4‐position of pyridine ring by the oxygen site (O‐centered nucleophile) of quinazolinone. The structures of all the compounds were confirmed by IR, ¹H NMR, ¹⁹F NMR, and ¹³C NMR spectroscopy as well as elemental analysis.     

Synthesis and characterization of tungsten carbonyl complexes containing N-methyl substituted urea and thiourea ligands

Six new mixed-ligand tungsten carbonyl complexes containing N-methyl substituted urea and thiourea of the type W(CO)₄[RCH₂N-(C=X)NH₂] where X?=?O or S and R?=?morpholine, piperidine and diphenylamine are reported. These have been prepared by refluxing hexacarbonyl tungsten(0) with corresponding ligands in THF to produce cis-disubstituted products, [(L-L)W(CO)₄] where L-L?=?a chelating bidentate ligand, morpholinomethyl urea (MMU), morpholinomethyl thiourea (MMTU), piperidinomethyl urea (PMU), piperidinomethyl thiourea (PMTU), diphenylaminomethyl urea (DAMU) and diphenylaminomethyl thiourea (DAMTU). The compounds have been characterized by elemental analysis, IR, electronic and ¹³C NMR spectra, magnetic moments and conductivity measurements. The IR spectra suggests that in all the complexes, the ligands are bidentate chelating, coordinating the metal through carbonyl oxygen or thiocarbonyl sulphur and the ring nitrogen or tert-nitrogen of diphenylamine. The CO force constants and CO–CO interaction constants for these derivatives have also been calculated using Cotton–Kraihanzel secular equations, which indicate poor π-bonding ability of the ligands. ¹³C NMR and electronic spectra reveal loss of cis-carbonyl ligands to produce cis-disubstituted tetracarbonyl derivatives. Molecular modeling studies have been carried out using Hyperchem release 7.52 which suggest a distorted octahedral geometry for these complexes.     

Synthesis of New Metal‐Free 1,4,8,11‐Tetraaza[14]annulene Derivatives Using 2‐Heteroaryl‐substituted Trimethinium Salts

The reaction of 2‐heteroaryl‐substituted trimethinium salts (A, B, and C) with aromatic 1,2‐diamines ( a , b , c , d , and e ) in acetonitrile/acetic acid leads to 6,13‐disubstituted 1,4,8,11‐tetraaza[14]annulene derivatives ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ). The UV–vis spectral behavior of these compounds was examined in acetonitrile. Elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR, and mass spectra confirm the molecular structure of the newly synthesized compounds.     

Synthesis,Dissociation Constants,and Antimicrobial Activity of Novel 2,3‐Disubstituted‐1,3‐thiazolidin‐4‐one Derivatives

In this article, a new series of 2,3‐disubstituted‐1,3‐thiazolidin‐4‐one derivatives have been designed, synthesized, and evaluated as antimicrobial agents. New compounds were prepared by the cyclization reaction of N‐substituted carboxylic acid hydrazide derivatives with mercaptoacetic acid. The structures of the obtained compounds were confirmed by means of IR, ¹H NMR, and ¹³C NMR spectra. The dissociation constants were determined using spectrophotometric method. All synthesized compounds were tested for their in vitro antibacterial and antifungal activities using the broth microdilution method.     

An Efficient Synthesis of Highly Optically Active 4-Substituted-2（5H）-furanones from Chiral 3-Bromo-2（5H）-furanone

Highly optically active 4-substituted-2(5H)-furanones 6a-6j were obtained in good yields with de≥98% by the tandem Michael addition/elimination reaction of chiral 3-bromo-2(SH)-furanone (4a), which was conveniently prepared starting from 2-furaldehyde under mild conditions. The products were identified on the basis of their satisfactory elemental analysis and spectroscopic data of IR, UV, ^1H NMR, ^13C NMR and mass spectra. The stereochemistry and absolute configuration of this type of compounds were established by the X-ray crystallographic study. The reaction provided a short and efficient synthesis of the interesting highly optically active 4-subsdtuted-2(5H)-furanones containing an active pyrimidine and a purine base group.     

Oxygen-17 NMR chemical shifts of esters

The ¹⁷O NMR spectra of some esters are discussed and are correlated with ¹³C NMR chemical shift and IR carbonyl streching band data.     

Synthesis and Visible Spectral Behaviour of Some New N‐Bridgehead Heterocyclic Cyanine Dyes Incorporating Pyrazolo (4,5‐b) Indolizine (Benzoindolizine)

The new unsymmetrical N‐bridgehead, apo (zeromethine), mono‐methine, dimethine, meso substituted tetramethine and styryl cyanine dyes incorporating pyrazolo (4,5‐b) indolizine (benzoindolizine) nuclei were prepared. Structural confirmation was carried out by elemental analyses, IR, H‐NMR, mass spectra and ¹³C‐NMR with the aid of carbon DEPT spectral data. The visible absorption spectra for the newly synthesized cyanines were examined in 95% ethanol.     

Syntheses and Spectroscopic Study of Some New N‐4‐Fluorobenzoyl Phosphoric Triamides; Crystal Structures of 4‐F‐C6H4C(O)N(H)P(O)R2, R = NH‐C(CH3)3, NH‐CH2C6H5, N(CH3)(CH2C6H5)

Some new N‐4‐Fluorobenzoyl phosphoric triamides with formula 4‐F‐C₆H₄C(O)N(H)P(O)X₂, X = NH‐C(CH₃)₃ ( 1 ), NH‐CH₂‐CH=CH₂ ( 2 ), NH‐CH₂C₆H₅ ( 3 ), N(CH₃)(C₆H₅) ( 4 ), NH‐CH(CH₃)(C₆H₅) ( 5 ) were synthesized and characterized by ¹H, ¹³C, ³¹P NMR, IR and Mass spectroscopy and elemental analysis. The structures of compounds 1 , 3 and 4 were investigated by X‐ray crystallography. The P=O and C=O bonds in these compounds are anti. Compounds 1 and 3 form one dimensional polymeric chain produced by intra‐ and intermolecular ‐P=O···H‐N‐ hydrogen bonds. Compound 4 forms only a centrosymmetric dimer in the crystalline lattice via two equal ‐P=O···H‐N‐ hydrogen bonds. ¹H and ¹³C NMR spectra show two series of signals for the two amine groups in compound 1 . This is also observed for the two α‐methylbenzylamine groups in 5 due to the presence of chiral carbon atom in molecule. ¹³C NMR spectrum of compound 4 shows that ²J(P,C_aliphatic) coupling constant for CH₂ group is greater than for CH₃ in agreement with our previous study. Mass spectra of compounds 1 ‐ 3 (containing 4‐F‐C₆H₄C(O)N(H)P(O) moiety) indicate the fragments of amidophosphoric acid and 4‐F‐C₆H₄CN⁺ that formed in a pseudo McLafferty rearrangement pathway. Also, the fragments of aliphatic amines have high intensity in mass spectra.     

Ultrasonic Assisted Synthesis of Naphthalene Substituted Schiff Base Derivatives and Their Antioxidant Activity Studies

New Schiff base derivatives, 2,2′‐[naphthalene‐2,7‐diylbis(oxy)]bis[N′‐substituted acetohydrazide] ( 4a‐m ) were synthesized by the acid catalyzed condensation of aryl/hetero aromatic aldehydes with 2,2′‐ [naphthalene‐2,7‐diylbis(oxy)]diacetohydrazide ( 3 ) under reflux temperature and ultrasonic irradiation. These Schiff base derivatives were confirmed through spectral characterization using IR, ¹H NMR, ¹³C NMR and mass spectra. All the synthesized compounds were screened for their antioxidant activity using DPPH free radical scavenging method.     

Application of Sulfinyl bis(2,4‐dihydroxythiobenzoyl) in the Synthesis of N‐Substituted 2‐Amino‐5‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles

One‐stage synthesis of N‐substituted 2‐amino‐5‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles is described. The compounds were prepared by the reaction of the sulfinyl bis(2,4‐dihydroxythiobenzoyl) (STB) with 4‐substituted 3‐thiosemicarbazides. STB was obtained from 2,4‐dihydroxybenzenecarbodithioic acid and thionyl dichloride. The structure of compounds was confirmed by IR, ¹H NMR, ¹³C NMR, and EI‐MS data.     

Synthesis and Reactions of Some New Benzo[a]phenothiazine‐3,4‐dione Derivatives

The reaction of 2,3‐dihydro‐2,3‐epoxy‐1,4‐naphthoquinone ( 4 ) with substituted anilines furnished the corresponding benzo[fused]heterocyclic derivatives 5 , 6 , 6a , 6b , 7 , 8 . Furthermore, treatment of benzo[a]phenothiazine derivative 7 with halo compounds, namely, ethyl bromoacetate, phenacyl bromide, dibromoethane, or chloroacetone afforded ether derivatives 11 , 12 , 13 , 14 , respectively. Moreover, the reaction of 11 with o‐substituted aniline gave the corresponding benzo[a]phenothiazin‐5‐one derivatives 15 , 16 , 17 and benzo[d][1,3]oxazin‐4‐one 18 , respectively. Finally, the chromenone derivative 19 was synthesized via the reaction of ester derivative 11 with salicyaldhyde in refluxing pyridine. The newly synthesized compounds were characterized by spectroscopic measurements (IR, ¹H NMR, ¹³C NMR, and mass spectra).     

1,6-六亚甲基二异氰酸酯自聚产物的结构表征

用IR与NMR表征了用醋酸钾为催化剂时 1,6 六亚甲基二异氰酸酯 (HDI)自聚产物的结构 .结果表明 ,自聚主产物是三聚体异氰脲酸酯 ,主要含有三聚体异氰脲基、异氰酸根 ,同时含有由杂质带来的微量氨基甲酸酯、脲基甲酸酯基、取代脲基、缩二脲基 .一维核磁谱及二维化学位移相关谱分辨出 7种羰基 ,一种NCO基 ,确定了氮上 8种不同取代结构的分子链连接情况 .通过建立理论模型 ,定量地描述了自聚产物的结构 .     

Synthese und Charakterisierung funktionalisierter β‐Hydroxydithiozimtsäuren und deren Ester. Komplexchemisches Verhalten gegenüber Nickel(II), Palladium(II) und Platin(II)

Synthesis and Analytical Characterization of Functionalized β‐Hydroxydithiocinnamic Acids and their Esters. Complex Chemistry towards Nickel(II), Palladium(II), and Platin(II) Starting from silyl‐protected 4‐hydroxy acetophenone ( 1 ) the 1,1‐ethenedihiolato complexes 3 – 5 were synthesised using carbon disulfide and potassium‐tert‐butylate as a base. After being deprotected, the resulting 4‐hydroxy‐substituted complexes 6 – 8 were esterified with DL‐α‐lipoic acid to obtain the compounds 9 – 11 . The resulting complexes were characterized using NMR spectroscopy, mass spectrometry and IR spectroscopy. 3‐substituted β‐hydroxydithiocinnamic acid methyl ester ( 12 ) was obtained via an analogous path of reaction using silyl‐protected 3‐hydroxy acetophenone ( 2 ), carbon disulfide and methyl iodide. After removing of the silyl group the resulting hydroxy group was esterified with DL‐α‐lipoic acid. Using the dithioacid ester 14 as a ligand the Ni^II ( 15 ), Pd^II ( 16 ) and Pt^II ( 17 ) [O,S] complexes were obtained.     

Photolysis of α,β‐Epoxyketones: A Green Synthesis of β‐Hydroxyenones through Tandem H‐Abstraction,Ring Cleavage and Isomerisation

The photochemical behavior of various substituted epoxycarbonyl compounds consisting of more than one possible photo‐labile site (i.e. δ‐hydrogen, β‐hydrogen and epoxide ring) has been investigated. These compounds on photo‐irradiation produced the β‐hydroxyenones in an eco‐friendly green approach. Mechanistically, these photo‐transformations have been envisaged to occur via an intramolecular β‐hydrogen abstraction by the carbonyl group of benzoyl moiety to generate the 1,3‐biradical followed by epoxide ring opening that isomerizes into the photoproducts. The photolysis of the probed epoxy ketones didn’t furnish any photoproduct through δ‐hydrogen abstraction, whatsoever. This exclusive preference for β‐H abstraction over δ‐H abstraction by carbonyl group has been vindicated by the MM2 energy mini‐ mized program for the investigated photochemical substrates. The structures of these photoproducts were established from the analysis of their spectral parameters (IR, ¹H/¹³C NMR and Mass) and single crystal X‐ray crystallography data.     

Synthesis of Novel Phthalazine Derivatives as Potential Anticancer and Antioxidant Agents Based on 1‐Chloro‐4‐(4‐phenoxyphenyl)phthalazine

A new series of phthalazine derivatives was synthesized from the reaction of 1‐chloro‐4‐(4‐phenoxyphenyl)phthalazine as a reactive starting material with different carbon, nitrogen, oxygen, and sulfur nucleophiles. The structural formulae of all products were confirmed and characterized by elemental analyses and spectral data (IR, ¹H NMR, ¹³C NMR, and mass spectra). Some of the synthesized derivatives were screened for their antitumor activity against four human tumor cell lines using MTT assay. In comparison with doxorubicin as standard drug, compounds 1 , 20 , and 25 showed the most potent cytotoxic effect. In addition, investigation of antioxidant activity revealed that hydrazinylphthalazine 20 has the highest activity.     

Synthesis and structure of some imines containing furoxan ring derived from isosafrole

A series of 14 imines containing furoxan and benzene rings has been prepared starting from isosafrole. The structure of reported compounds have been confirmed by elemental analysis, EI MS, UV, IR, and NMR spectroscopy. It is shown that, on treatment with Na₂S₂O₄, the nitro group on the benzene ring was reduced to amino group, but the N→O group of the furoxan ring was not. The ¹H‐ and ¹³C NMR signals are assigned based on their spin‐spin splitting patterns, in some cases, NOESY and HMBC spectra are used. The NOESY spectra indicate that for reported imines, the benzene and the furoxan rings could not be co‐planar; the imine group has E‐configuration.     

Thiophene‐2,5‐dicarboxylic acid bis‐aryl(alkyl) amides

A base‐catalyzed condensation of diacetamido sulfides [(RNHCOCH₂)₂S)] with glyoxal affording thiophene‐2,5‐dicarboxylic acid bis‐aryl(alkyl)amides has been accomplished under mild conditions. Excellent results were readily obtained when R was a substituted 3‐nitrophenyl, 4‐nitrophenyl, 4‐chlorophenyl group, but the yield was poor when R was cyclohexyl. Unknown compounds were characterized by elemental analyses, IR, ¹H, and ¹³C NMR techniques. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:503–506, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20153     

New phosphoric triamides: Chlorine substituents effects and polymorphism

New phosphoric triamides 1–10 were synthesized by the reaction of N‐2,4‐dichlorobenzoyl phosphoramidic dichloride with various cyclic aliphatic amines, and the products were characterized by ¹H, ¹³C, ³¹P NMR, and IR spectroscopy and elemental analysis. Surprisingly, the ¹H NMR spectra of compounds 1–7 demonstrate long‐range ⁴J(H,H) coupling constant from 1.5 to 1.9 Hz. Comparison of the NMR and IR spectra of N‐benzoyl, N‐4‐chlorobenzoyl, and N‐2,4‐dichlorobenzoyl phosphoric triamide analogues indicates that N‐2,4‐dichlorobenzoyl derivatives have the most upfield δ(³¹P) and the highest ν(CO) values. The crystal structures of 3 , 4 , 6 , 6a , and 10 have been determined by X‐ray crystallography. Interestingly, the structures of 6 and 6a are polymorphic. All structures form dimers through strong, intermolecular  PO···H N hydrogen bonds. The dimers connect to each other via weak C H···Cl and C H···OH bonds to produce two‐dimensional polymeric chains for 4 and three‐dimensional networks for others. Among new synthesized N‐2,4‐dichlorobenzoyl phosphoric triamides, one indicated polymorphism. All structures were characterized by ¹H, ¹³C, ³¹P NMR, and infrared spectroscopy and elemental analysis. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:168–180, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20592