Facile synthesis of two oxocan derivatives using some chemical strategies

There are several studies for the synthesis of oxacycle derivatives using some reagents which require special conditions have been reported. The aim of this study was to synthesize two oxocan derivatives from either imidazole or 2-methylimidazole. The chemical structure was evaluated through both ¹H NMR and ¹³C NMR spectroscopic analysis. The results showed a moderate yielding from oxocan derivatives. It should be mentioned that reagents used in this investigation are not expensive and do not require special conditions for handling.     

17O NMR spectroscopy of transition metal carbonyls

NMR spectra of ¹⁷O in natural abundance have been obtained for a range of metal carbonyls. Linewidths of less than 10 Hz for the derivatives of Cr, Mo, W and Fe have been observed, although they are slightly larger for the derivatives of metals having an electric quadrupole moment. Comparison with the corresponding ¹³C NMR data shows that: (i) the chemical shift ranges are comparable, (ii) the ordering of chemical shifts is not very different, (iii) the linewidths are more favourable for ¹⁷O than ¹³C for some Mn and Co derivatives and allow an extension of the range of temperature in which information on the fluxional dynamics are obtainable in the rapid exchange limit.     

Preparation and complete 1 H and 13C assignment of some pentacyclo[5.4.0.02,6.03,10.05,9]undecane‐8,11‐dione (PCUD) derivatives

The preparation of a number of alkyl and alkoxy derivatives of pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane‐8,11‐dione derivatives utilising a cheap, practical, low energy, ‘green’, single‐pass continuous flow photochemical reactor is reported. Their ¹ H and ¹³C NMR spectra are fully assigned, revealing some general characteristics not previously reported for this class of compound, which should aid the assignment and prediction of the NMR spectra of PCUD derivatives. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis of Heterocyclic Pentavalent Phosphorus Compounds from Phosphite Derivatives and Indane-1,2,3-Trione

Reaction of trialkylphosphite derivatives with indane-1,2,3-trione proceeds smoothly at room temperature to afford the corresponding heterocyclic pentavalent [P(V)] phosphorus compounds via an intermolecular [4+1] cycloaddition reaction in excellent yields under solvent-free conditions. We also used dimethylphosphite and diethylphosphite instead of trialkylphosphites in this reaction, but the corresponding pentavalent phosphorus compounds were not isolated, and in both cases phosphate derivatives were obtained. The structures of the products were deduced from their IR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectra, and mass spectrometry.     

13C NMR spectroscopy of cyclopropane derivatives. 1—monocyclic compounds

The ¹³C NMR data of an appreciable number of cyclopropane derivatives have been collected. Most of the spectra were recorded by ourselvesand some were taken from the Literature. With a view to furthering the useof ¹³C NMR spectroscopy as a diagnostic tool in this field, we havemeasured not only the chemical shifts,δ, but also the coupling constants ¹J(CH). It is shown that both embody valuable structural information.     

Substituent dependence of stable conformations in triazolobenzothiazines

From the ¹H and ¹³C NMR spectra of angularly condensed triazolobenzothiazine derivatives it was established that these compounds can be classified into two conformation types, depending on the substituents. The 10-methyl-3-carbethoxy derivatives are cis-anellated, conformationally flexible systems, where one of the aromatic hydrogens (H-9) and one of the methoxy substituents (8-OMe) of the benzothiazine skeleton on the one hand, and the 1-aryl ring on the other, lie close to each other in the preferred conformer. By assuming this conformation, the molecules avoid the steric hindrance of the 10-Me and 1-aryl groups. All compounds unsubstituted on the angular C-10 atom, and the 3-aryl-substituted derivatives of the 10-Me analogues, occur in a different conformation, containing the 1-aryl ring well removed from H-9 and the 8-OMe group.     

Head-to-tail Aggregates of Sulfonatomethylated Calix[4]resorcinarene in Aqueous Solutions

Two amphiphilic water-soluble sulfonatomethylated calix[4]resorcinarene derivatives were studied by various ¹H NMR techniques (¹H NMR titration, 2D NOESY, NMR diffusion measurements). The derivative with methyl moieties at the lower rim (1) was found to be non-aggregated in the range 0–10 mM in aqueous solutions. Lengthening of the lower rim substituent to pentyl (2) results in self-aggregation of 2 in aqueous solutions with the aggregation number varying from 3 at 1 mM to 20 at 10 mM. The 2D NOESY ¹H NMR spectroscopy data reveal an unusual head-to-tail packing mode in aqueous solutions, resulting from the cooperative effect of weak hydrophobic interactions. Binding of guests (tetramethylammonium and N-methylpyridinium) results in additional stabilization of the aggregates whilst the head-to-tail packing mode of the aggregate is retained.     

13C-NMR study of cellulose derivatives in the solid state

The application of NMR for natural organic compounds has been carried out from the early history of NMR. But they reported on the liquid state NMR and the samples were limited to the materials which dissolved in proper solvents. It has been possible to measure the samples in the solid state in 1970s and is widely used as a familiar analytical method in 1980s. Whereas some of the data is inadequate, concerning cellulose derivatives, in particular, only nitrate and acetate were reported by Patterson¹ and Doyle,² respectively. In this paper, the ¹³C CP/MAS solid state NMR spectra of several cellulose derivatives are shown and the relationship between the structure and spectrum is discussed.     

Application of the N-hydroxymethyl group to the stereoselective synthesis of (3S,4S)-3-aminodeoxystatine derivatives

Stereoselective synthesis of two 3-aminodeoxystatine derivatives was achieved. Chiral γ-amino-α,β-unsaturated esters containing an N-aminomethyl group undergo the stereoselective conjugate addition with an internal carbamate or amide nitrogen nucleophile. The diastereoselectivity was about 10:1 by ¹H NMR. Thus, the 3-aminodeoxystatine derivatives were prepared from commercially available N-Boc-l-leucine in nine steps in overall yields of 26% and 20% for the benzyl carbamate and the acetamide derivatives, respectively.     

Structure of cyanoethylation products of 1,2,3-triazolecarboxylic acid derivatives

The cyanoethylation of derivatives of 5-chloro-1,2,3-triazolecarboxylic acids was studied, and it was shown by mass spectrometry and¹H NMR spectroscopy that the only products of this reaction are 2-N-cyanoethyl derivatives.Center for the Chemistry of Drugs, All-Russian Chemicopharmaceutical Scientific-Research Institute, Moscow, 119021. Translated from Khimiya Geterotsiklicheskikh Soedienii, No. 10, pp. 1369–1374, October 1994. Original article submitted October 14, 1994.     

Curing Kinetics and Thermal Stability of Diglycidyl Ether of Bisphenol‐A Using Mixtures of Heterocyclic Derivatives of Stannanes and 4,4′‐Diaminodiphenylsulfone

Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of varying molar ratios of derivatives of stannanes to 4,4'-diaminodiphenylsulfone (DDS) was investigated by the dynamic differential scanning calorimetry. The derivatives were synthesized by reacting 1 mole of biguanide (B) with 1 mole of phenylethyltindihydride (PETH) or phenylmethyltindihydride (PMTH) or phenylbutyltindihydride (PBTH) and designated as BPETH or BPMTH or BPBTH respectively. These derivatives were characterized by elemental analysis and spectroscopic techniques such as IR, ¹H NMR, ¹³C NMR and ¹¹⁹Sn NMR. The mixtures of these derivatives to DDS at ratios of 0∶1, 0.25∶0.75, 0.5∶0.5, 0.75∶0.25 and 1∶0 were used to investigate the curing behaviour of DGEBA. The multiple heating rate method (5, 10, and 15 and 20 ℃•min^－1) was used to study the curing kinetics of epoxy resins. The thermal stability of the isothermally cured resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere.     

13C and 77Se NMR of some organometallic derivatives with Ti,Zr and Hf

¹³C and ⁷⁷Se NMR was carried out on dicyclopentadienyl derivatives of Ti, Zr and Hf with selenium bonded directly to the metal. Although ¹³C NMR is not sensitive to different substitution, ⁷⁷Se NMR is valuable and reflects the influence of the different organic substituents and the nature of the metals bonded to the selenium atom.     

Study of Dehydrocoupling Reactions of Diorganotin Dihydrides R^1R^2SnH2 with Biuret

The reaction of unsymmetrical phenylmethyltin dihydride （PhMeSnH2）, phenylethyltin dihydride （PhEtSnH2）, phenylbutyltin dihydride （PhBuSnH2） and butylmethyltin dihydride （BuMeSnH2） with biuret （HAL） proceeds via SnH/NH dehydrocoupling to afford the corresponding tetra-coordinate cyclic products. The reactions in the molar ratios of 1 ： 1, 2 ： 1 and 1 ： 2 have been studied. The yellow derivatives so isolated were soluble in polar solvents and insoluble in nonpolar solvents. It was found that 1 ： 1 reaction went to completion while 2 ： 1 and 1 ： 2 did not go to completion. The derivatives had been characterized by elemental analysis and spectroscopic techniques viz. IR, ^1H NMR, ^13C NMR, ^119Sn NMR. DSC and TGA of the reaction products have also been studied. All the derivatives were thermally stable upto （1904- 10）℃ and degradation occurred after that.     

A new route to novel 10-deoxoartemisinins

A series of novel 10-deoxoartemisinin derivatives was synthesized with high regioselectivity and yields using Heck reactions from 10β-allyldeoxoartemisinin. The configuration of the double bond of the product was determined from ¹H NMR coupling constants (J_2′-3′).     

QSAR studies of phenylhydrazine-substituted tetronic acid derivatives based on the 1H NMR and 13C NMR chemical shifts

The quantitative structure–activity relationship models of 40 phenylhydrazine-substituted tetronic acid derivatives were established between the ¹H nuclear magnetic resonance (NMR) and ¹³C NMR chemical shifts and the antifungal activity against Fusarium graminearum, Botrytis cinerea, Rhizoctonia cerealis, and Colletotrichum capsici. The models were validated by R, R², R_A², variance inflation factor, F, and P values testing and residual analysis. It was concluded from the models that the ¹³C NMR chemical shifts of C8, C10, C7, and the ¹H NMR chemical shifts of Ha contributed positively to the activity against Fusarium graminearum, Botrytis cinerea, Colletotrichum capsici, and Rhizoctonia cerealis, respectively. The models indicated that decreasing the election cloud density of specific nucleuses in compounds, for example, by the substituting of electron withdrawing groups, would improve the antifungal activity. These models demonstrated the practical application meaning of chemical shifts in the quantitative structure–activity relationship study. Furthermore, a practical guide was provided for further structural optimization of the antifungal phenylhydrazine-substituted tetronic acid derivatives based on the ¹H NMR and ¹³C NMR chemical shifts.     

A Convenient Synthesis and Biological Research of Novel 5,6,7,8‐Tetrahydro‐1,6‐naphthyridin‐2(1H)‐one Derivatives Hydrochloride as Cytotoxic Agents

A series of 5,6,7,8‐tetrahydro‐1,6‐naphthyridin‐2(1H)‐one derivatives hydrochloride were obtained using a convenient and mild method from 4‐piperidone monohydrate hydrochloride. The newly synthesized compounds and their derivatives were characterized by ¹H NMR, ¹³C NMR, and high‐resolution mass spectrometry. Furthermore, cytotoxicity in vitro of the synthesized compounds were screened using MTT or CCK8 assay. The results showed that some of the compounds showed potential antitumor activity. Among of them, compound 10a had effects against tumor cells (MOLM‐13), and the half maximal inhibitory concentration value was 76 μmol/L.     

Antitubercular Activity and Synergistic Study of Novel Pyrazole Derivatives

A series of 20 novel pyrazole derivatives were designed and prepared, characterized by ¹H‐NMR, mass spectra (ES‐MS), ¹³C‐NMR, and elemental analysis. The synthesized compounds were then evaluated for their growth inhibitory activity against Mycobacterium smegmatis mc² 155 initially. Rifampicin was used as standard reference. In this screening, derivatives 9 , 10 , and 11 presented superior inhibition compared with standard. Later, these three compounds were exposed for their Mycobacterium tuberculosis H37Rv inhibitory assay using rifampicin as standard reference. Encouraging M. smegmatis mc² 155 inhibition (9 μg/mL), M. tuberculosis H37Rv inhibition (1.9 μg/mL), and synergism with the first‐line and second‐line antibiotics made compound 10 as lead and safe antitubercular agent among the series.     

Aqua-mediated rapid and benign synthesis of 1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-one-appended novel 2-arylidene indanones of pharmacological interest at ambient temperature

In the present investigation, a green aqua-mediated protocol for the synthesis of novel 2-arylidene indanone derivatives from 1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-one was unveiled. The application of water in organic reactions as a solvent is one of the incredible tools of green chemistry as reactions can be carried out under benign conditions minimizing environmental hazard and chemical waste. A library of novel 2-arylidene indanone derivatives are synthesized in good to excellent yield by utilizing the green potential of water as a solvent. The structures of all novel 2-arylidene indanone derivatives reported herein are confirmed using Fourier-transform infrared spectroscopy (FTIR), ¹H NMR, ¹³C NMR, ¹⁹F NMR, distortionless enhancement by polarization transfer (DEPT), and High Resolution Mass Spectrometry (HRMS) techniques.     

Synthesis of Novel β‐Lactams from Phenothiazin‐10‐ylacetic Acid

The first synthesis of 3‐phenothiazine‐β‐lactams is herein reported. Thirteen new derivatives of β‐lactams were synthesized using various Schiff bases and (phenothiazin‐10‐yl)acetic acid, which in turn was prepared starting from phenothiazine. The sole product of the Staudinger ketene–imine [2 + 2] cycloaddition reaction is the trans‐β‐lactam. All the synthesized compounds were characterized by elemental analyses and spectral (IR, ¹H‐NMR, and ¹³C‐NMR) data.     

Carbon-13 nuclear magnetic resonance spectroscopy: VIII—aliphatic hydrocarbon derivatives

Carbon-13 NMR chemical shifts of several series of aliphatic hydrocarbon derivatives–-substituted methanes, ethanes, isopropanes, n-propanes and n-butanes–-were found to have a linear relationship with σ-electron densities (Q^σ) calculated by the method of σ-included ω-HMO. A plot of the ¹³C NMR chemical shift of a given carbon in a substituted propane versus that of the corresponding carbon in a substituted butane showed a good linearity with a slope of unity. The values of the ¹³C chemical shifts of the n-butyl derivatives converged rapidly to a constant value as the distance from the substituent increased. Accordingly, the value for the δ-carbon was found to be constant regardless of the substituent. These results show that the ¹³C NMR chemical shifts of aliphatic hydrocarbon derivatives are mainly dependent on inductive effects. The convergence shown by the experimental results is supported by the calculated results of the Q^σ values of the n-butyl derivatives.