Factors Affecting the Stability of Platinum(II) Complexes with 1,2,4-Triazolo[1,5-a]pyrimidine Derivatives and Tetrahydrothiophene-1-Oxide or Diphenyl Sulfoxide

The platinum(II) complexes of general formula [PtCl₂(dstp)(S-donor)] were dstp 5,7-dimethyl-1,2,4-triazolo[1,5-a]-pyrimidine (dmtp), 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp), 5-methyl-7-isobutyl-1,2,4-triazolo[1,5-a]pyrimidine (ibmtp) or 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp), whereas S-tetrahydrothio-phene-1-oxide (TMSO) or diphenyl sulfoxide (DPSO) were synthesized in a one-pot reaction. Here, we present experimental data (¹H, ¹³C, ¹⁵N, ¹⁹⁵Pt NMR, IR, X-ray) combined with density functional theory (DFT) computations to support and characterize structure–spectra relationships and determine the geometry of dichloride platinum(II) complexes with selected triazolopyrimidines and sulfoxides. Based on the experimental and theoretical data, factors affecting the stability of platinum(II) complexes have been determined.     

Assignment of all Diastereomers of Perhydrofluorene in a mixture using 13C NMR spectroscopy

By hydrogenation of fluorene 1 using different catalysts, mixtures containing variable amounts of the six possible diastereomers of perhydrofluorene 2 were obtained. The ¹³C NMR spectra of all diastereomers have been determined in these mixtures whithout previous separation procedures. By molecular mechanics calculations the structures of the preferred conformations were simulated for all diastereomers. The substituent induced ¹³C NMR chemical shifts in conformers were calculated by using increments for the non-bonding 1,3-synaxial interactions. Three stereochemical increments, combined with the shift values found earlier by Beierbeck and Saunders, were sufficient to calculate the chemical shift differences of conformers empirically. The assignment of relative configurations of the diastereomers was possible by comparison of the empirically calculated and experimental ¹³C chemical shifts of the clearly distinguishable bridgehead carbons. The difference between calculated and experimentally determined shift values was only 1.3 ppm, averaged over all bridgehead carbons.     

Substituent Effects on 13C Chemical Shifts of Aromatic Carbons in β-O-4 and β-5 type Lignin Model Compounds

Abstract

Substituent effects on the chemical shifts of aromatic carbons in lignin model compounds have been elucidated from ¹³C NMR spectra of guaiacyl and syringyl type monomerio and β-O-4 model compounds and guaiacyl type β-5 model compounds. Evaluation of the observed values of substituent chemical shift (SCS) for the aromatic carbons leads to elucidation of a generalized SCS additivity rule, for estimation of the chemical shifts of aromatic carbons in ring A of β-O-4 and β-5 type substructures in model compounds and in ring B of β-O-4 substructures in lignin preparations, with errors of less than 1 ppm. The rule is applicable to substructures of both guaiacyl and syringyl types, using an appropriate parent compound as reference instead of benzene. Signals in the aromatic region of the ¹³C NMR spectra of β-O-4 and β-5 type model compounds are reassigned on the basis of the observed SCS's as well as APT spectra of the compounds.     

Separation and spectral data of the six isomeric ozonides from methyl oleate

The structures of the products obtained on ozonation of methyl oleate have been re-examined. The assignments for the six isomeric ozonides of methyl oleate have been made by¹H and¹³C nuclear magnetic resonance (NMR), which were consistent with the retention times observed in high-performance liquid chromatography; the assignments were confirmed by mass and infrared spectroscopy. Two triplets for the ozonide ring protons of thecis andtrans isomers in the normal (MOO1) and the two cross ozonides (MOO1 and MOO3) can be resolved by 400 MHz NMR. For MOO1 and MOO3, where the two ring carbons are equivalent, two peaks for the ring carbons of each cross ozonides are resolved in the¹³C NMR spectra, one for thecis and one for thetrans isomer. For MOO2, four peaks for the ring carbons are resolved in the¹³C NMR spectra, two for thecis and two for thetrans isomer.     

Nuclear magnetic resonance characterization of reaction products of interesterification of peracetylated α-d-glucopyranose and fatty acid methyl esters

Mono- and diesters of fatty acids of peracetylated α-d-glucopyranose were prepared by chemical interesterification. Substituent-induced chemical shift effects on the carbonyl carbons rather than the ring carbons and proton atoms unambiguosly show the fatty acyl substituents to be at C1 in the monosubstituted, and at C1 and C6 in the disubstituted products. ¹H nuclear magnetic resonance (NMR) integration data before and after interesterification complemented ¹³C chemical shift data in verifying the molecular structures. Empirical data from classical ¹H and ¹³C NMR experiments thus provide a simple self-contained method for determining the number and position of fatty acyl substituents, and the anomeric compositions of peracetylated glucose fatty esters.     

Tandem Ring-Opening/Double Ring-Closing Synthesis of 1,2,4-Triazolo[1,5-a]pyridines from Chromone-Containing Acrylonitriles

We studied a reaction of chromone-containing acrylonitriles and cyanoacrylates with acid hydrazides. This reaction turned out to be a method for the synthesis of salicyloyl-substituted 1,2,4-triazolo[1,5-a]pyridines. The synthesis developed is a tandem ring-opening/double ring-closing process. This synthetic approach is characterized by low toxic solvents (ethanol, butanol) and mediator (Et₃N), 37–84% yields, non-chromatographic isolation of products, and substrate tolerance (59 examples).     

A novel synthesis of indeno[2',1': 5,6] pyrido[2,3- d ][1,2,4]triazolo[4,3- a ]pyrimidines

Reaction of 5-(4-chlorophenyl)-2-thioxo-2,3-dihydro-1H-indeno[2',1':5,6] pyrido[2,3-d]pyrimidine-4,6-dione with hydrazonoyl chlorides gave 1,2,4-triazolo[4,3-a]pyrimidine derivatives regioselectively in good yields. The structures of the newly synthesized compounds are established on the basis of chemical and spectroscopic evidence as well as their synthesis by alternative methods.     

Dehydration of 2-(2-Arylethyl)-2-hydroxy-4-oxopentanoic Acids and their hydrazones to form heterocycles

Dehydration of 2-(2-arylethyl)-2-hydroxy-4-oxopentanoic acids 1 with hydrochloric acid/acetic acid, affords 3-(2-arylethyl)-5-hydroxy-5-methyl-2(5H)-furanones 4 . Compounds of type 1 and 4 represent suitable precursors for the formation of pyridazin-3-ones 7 as they smoothly react with hydrazine. A new series of s-triazolo[4,3-b]pyridazin-3-ones 12 and tetrazolo[1,5-b]pyridazines 15 are obtained from the 3-chloropyridazines 11 upon treatment with semicarbazide and sodium azide, respectively. Reaction of 11 with phenyl- acetyl-hydrazine provides 3-benzyl-6-phenyl-8-(2-phenyl-ethyl)-s-triazolo[4,3-b]pyridazine 13 via dehydrative cyclization of the intermediate 14 which was clarified to exhibit tautomeric equilibria between enol–hydrazine form A and keto–hydrazine form B by means of ¹H and ¹³C NMR spectroscopy. Attempts to synthesize 3-alloxy-pyridazines 18 by reacting 11 with sodium alloxide afford N-allyl compounds 17 .     

三唑并嘧啶磺酰胺类化合物的合成及除草活性

以5-氨基-3-巯基-1,2,4-三唑为起始原料,经氧氯化、胺解和环合,制得了9个1,2,4-三唑[1,5-a]嘧啶磺酰胺类化合物,产物结构经IR和1H NMR验证,并测定了它们的除草活性。     

17O NMR Studies of Yeast Ubiquitin in Aqueous Solution and in the Solid State

We report a general method for amino acid-type specific ¹⁷O-labeling of recombinant proteins in Escherichia coli. In particular, we have prepared several [1-¹³C,¹⁷O]-labeled yeast ubiquitin (Ub) samples including Ub-[1-¹³C,¹⁷O]Gly, Ub-[1-¹³C,¹⁷O]Tyr, and Ub-[1-¹³C,¹⁷O]Phe using the auxotrophic E. coli strain DL39 GlyA λDE3 (aspC⁻ tyrB⁻ ilvE⁻ glyA⁻ λDE3). We have also produced Ub-[η-¹⁷O]Tyr, in which the phenolic group of Tyr59 is ¹⁷O-labeled. We show for the first time that ¹⁷O NMR signals from protein terminal residues and side chains can be readily detected in aqueous solution. We also reported solid-state ¹⁷O NMR spectra for Ub-[1-¹³C,¹⁷O]Tyr and Ub-[1-¹³C,¹⁷O]Phe obtained at an ultrahigh magnetic field, 35.2 T (1.5 GHz for ¹H). This work represents a significant advance in the field of ¹⁷O NMR studies of proteins.     

Effects of Solvation and Ionization on 13C NMR Spectra of Lignin Model Compounds,Spruce Milled Wood Lignin and Kraft Lignin

The effects of alkali and polar aprotic solvent on the aromatic carbons signals in ¹³C NMR (Carbon-13 nuclear magnetic resonance) spectra of lignin model compounds and spruce milled wood lignin (MWL) were studied. It was found that in 1 M aqueous NaOH signal shifts of C-1 and C-4 carbon atoms in the aromatic ring were the most noticeable in lignin models with free phenolic hydroxyl groups, which are ionized under the conditions. A similar effect in the spectra of the studied model compounds was observed in 0.5 M aqueous NaOD-deuterated dimethyl sulfoxide (DMSO) mixture (DMSO: water ratio 3:7 v/v). The model data help explaining changes in the ¹³C NMR spectra of MWL and lignin in situ dissolved in spruce kraft black liquor caused by ionization. In the ¹³C NMR spectra of spruce black liquor the signals of phenolic and non-phenolic lignin units are clearly separated and do not overlap with the signals of the carbon atoms of carbohydrates and other aliphatic products of wood degradation. The data obtained are useful in understanding the important role of solvation and ionization processes leading to lignin solubilization.     

Structural analysis of cellulose triacetate polymorphs by two-dimensional solid-state C-C and H-C correlation NMR spectroscopies

For the elucidation of the crystal structures of the two crystalline allomorphs of cellulose triacetate (CTA), namely CTA I and CTA II, two-dimensional (2D) solid-state through-bond ¹³C-¹³C and ¹H-¹³C correlations NMR techniques applied to the two crystalline allomorphs of CTA. As a result, the ¹³C and ¹H chemical shifts of the glucopyranose ring of CTA I and CTA II were completely assigned by the 2D NMR spectra of these allomorphs. On the 2D ¹³C-¹³C correlation spectrum of CTA II, two sets of the ¹³C-¹³C correlations from C1 to C6 were observed. This indicated that the CP/MAS ¹³C NMR spectrum of CTA II can be characterized by its overlapping of the ¹³C subspectra of two kinds of 2,3,6-triacetyl-anhydroglucopyranose units and that there are two magnetically non-equivalent sites in the unit cell of CTA II. In the case of CTA I, the numbers of respective ¹³C and ¹H shifts of CTA I agreed with the those of the glucopyranose residue in the allomorph, strongly suggesting that the asymmetric unit of CTA I is only one glucose residue. In addition, conformational differences in the exocyclic C5-C6 bonds between CTA I and CTA II were strongly suggested by the notable differences in the ¹H and ¹³C chemical shifts at the C6 sites of these allomorphs.     

13C nuclear magnetic resonance of mono-and dihydroxy saturated and unsaturated fatty methyl esters

¹³C nuclear magnetic resonance spectra were obtained for methyl esters oferythro- andthreo-9,10-dihydroxystearates, for 12-hydroxy-cis- andtrans-9-octadecenoates, and forthreo-12,13-dihydroxy-cis-andtrans-9-octadecenoates.Erythro andthreo compounds may be distinguished easily by the difference in the chemical shifts of the carbons alpha to the hydroxy-bearing carbons. Monohydroxy compounds are easily distinguished fromvicinal dihydroxy compounds by differences in chemical shifts of both the hydroxy-bearing carbons and of the carbons alpha to them. The presence of a hydroxy-bearing carbon beta to a double bond results in the two carbons of the double bond of a hydroxy-bearing carbon beta to a double bond results in the two carbons of the double bond having different chemical shifts, with the numerical values being different for thecis andtrans isomers. The chemical shift of a carbon alpha to both a doubly bonded carbon and a hydroxy-bearing carbon is influenced both by the geometry of the double bond and the number of hydroxy-bearing carbons. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

NMR studies of water‐borne polyurethanes

A series of water‐borne polyurethanes were prepared by prepolymerization process. Isophorone diisocyanate, polyester diol, and dimethylol propionic acid were used to conduct the reaction. ¹H‐ and ¹³C‐NMR spectra of the raw materials and products thereof were measured with a high‐resolution spectrometer, and their chemical shifts were assigned. ¹H‐ and ¹³C‐NMR spectra of urethane group and urea group were compared. The chemical shifts of side products from the reaction between water and the isocyanate group were also analyzed. Much useful information may be obtained from the NMR analysis of this kind of polyurethanes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 257–260, 2003     

Investigation of the cellulose/LiCl/dimethylacetamide and cellulose/LiCl/N-methyl-2-pyrrolidinone solutions by 13C NMR spectroscopy

The cellulose/lithium chloride/dimethylacetamide (DMAc) and cellulose/lithium chloride/N-methyl-2-pyrroilidinone (NMP) solutions were investigated by ¹³C NMR spectroscopy. Well-resolved spectra were obtained for both solutions and indicated that cellulose was present in these systems in the form of underivatized cellulose. The change in ¹³C chemical shifts of DMAc and NMP in the presence of LiCl and LiBr was compared with that of several salt/aprotic solvents, and the results point to the existence of a cellulose–LiCl–DMAc (or NMP) complex in which the lithium cation is strongly bound to the amide carbonyl oxygen and the chloride anion involved in the dissociation of the cellulose hydrogen bonds. Spin–lattice relaxation times (T₁ of the ¹³C carbons of the solvent molecules, DMAc and NMP, show a large decrease in T¹ for all solvent carbons upon addition of LiCl. Further decrease in T₁ is observed when cellulose is introduced to the LiCl/NMP but not to the LiCl/DMAc systems. These observations are attributed to slower molecular motions of DMAc and NMP in the presence of LiCl, and, in the case of NMP, in the presence of cellulose.     

Addition of thianthrene cation radical to non-conjugated dienes—Part I: Addition to one double bond

Reaction of thianthrene cation radical tetrafluoroborate and hexafluorophosphate with an excess of 1,4-hexadiene, 1,5-hexadiene, 1,7-octadiene, 1,8-nonadiene and 1,9-decadiene gave, in each case, a mixture of bis- and monoadduct from addition to one of the diene’s double bonds. Addition to both double bonds did not occur. The monoadduct of each diene and the bisadduct (7a) of 1,5-hexadiene were isolated. All monoadducts and 7a were characterized with ¹H and ¹³C NMR spectroscopy. By reaction on activated alumina adducts were converted into (E)- and (Z)-(5-thianthreniumyl)dienes, all of which were characterized with ¹H and ¹³C NMR spectroscopy. The monoadduct (6a) of 1,4-hexadiene and the bisadduct 7a were characterized with X-ray crystallography.     

Tautomerism and Reactions of 1H-1,2,4-Triazole-5-thiones with Hydrazonoyl Halides

The acid dissociation constants (K_a) of a series of 3,4-diaryl-1H-1,2,4-triazole-5-thiones ( 1 ) were determined and were found to correlated linearly with Hammett substituent constants; log K_a = 1.06 σ_x − 11.01. Such a result indicates that 1 exists essentially in one tautomeric form namely the thione form. Reactions of 1 with hydrazonoyl chlorides 2 gave the thiohydrazides 5 . Similiar reaction of 3-phenyl-1H(4H)- 1,2,4-triazole-5-thione 1g with 2a gave the thiohydrazide 5h which was converted into 1,3,5-triphenyl-1,2,4-triazolo[3,4-c]-1,2,4-triazole ( 9 ). The latter was also prepared from 3-phenyl-5-methylthio-4H-1,2,4-triazole ( 6 ) and 2a . The mechanism of the reaction of 1 with 2 is discussed.     

Copolymers of acrylonitrile with some furans and their Diels-Alder adducts

Copolymers of acrylonitrile with furan, 2-methylfuran and with 2,5-dimethyl furan have been prepared by free radical copolymerizations, and their ¹³C spectra examined for evidence of the three types of structure that formed, according to previous studies. We have characterized the Diels-Alder adducts of acrylonitrile with furan and with 2-methylfuran, and have found that they may also copolymerize with acrylonitrile by addition at their double bonds. The enchained adducts were most readily recognized in the ¹H spectrum by shifts at 4.8 and 4.6 ppm respectively from protons at the oxygen bridgehead. The ¹³C spectra of these various polymers have been assigned with the aid of model compounds. Below δ=60 ppm the nitrile shift was dispersed over a larger range of shifts than is found in PAN itself, and was joined by the shifts of unsaturated carbon atoms and of carbon atoms linked to the oxygen atoms within these structures. Above 60 ppm the shifts of carbons in acrylonitrile units were found to be perturbed systematically from their normal places by the presence of neighbouring structures formed from the different furan-containing molecules. In both the ¹H and ¹³C spectra shifts characteristic of the end groups from the AIBN initiator were noted. Fine structure in the spectra was attributed to monomer sequence effects and to the tactic structure of the polymer. Chiral centres appeared to be created from the furan rings at random, at least when protonated carbons were the site of initial attachment, but the mode of addition to the ring—whether cis, trans or both, was not certain. Assignments were made of bands in the i.r. spectra to modes of vibration of the units formed from the furan monomers.     

Biosynthesis of hydrocarbons by algae: Decarboxylation of stearic acid to N-heptadecane inAnacystis nidulans determined by13C- and2H-labeling and13C nuclear magnetic resonance

The distribution of isotopic labels inn-heptadecane enriched from [1,2-¹³C] and [2-¹³C, 2-²H₃) acetates byAnacystis nidulans has been determined by¹³C nuclear magnetic resonance (¹³C NMR). Labeling with [1,2-¹³C] acetate is consistent with assembly from¹³C−¹³C units derived from an acetate “starter” group and 8 malonate units, as in fatty acid biosynthesis, followed by production of a methyl group through bond cleavage of the terminal¹³C−¹³C unit. A comparison of the hydrocarbon with palmitic acid (the only fatty acid produced in sufficient amount for NMR analysis) enriched from [2-¹³C,2-²H₃]acetate by the same culture shows that they have retained the same fraction of²H at corresponding sites, and have therefore undergone identical biosynthetic and hydrogen-deuterium exchange processes, as would be expected ifn-heptadecane originates from de novo-synthesized stearic acid. NRCC No. 18251.     

Dechema corrosion handbook Vol. 3 Edited by D. Behrens,VCH Verlagsgesellschaft,Weinheim Frankfurt am Main, 1988. pp. ix + 282, price £286.00 (subscription price to series £238.00 per volume) ISBN 3-527-26654-2

4-Phenyl-5-aminopyrazole 2 obtained from phenylcyanoacetaldehyde 1 and hydrazine hydrate reacted with diethyl malonate to give 3-phenyl-5,7-dioxopyrazolo[1,5-a]pyrimidine 3 , used as the key compound in the synthesis of arylazo dyes. The key compound 3 was coupled with various aryldiazonium salts 4 to yield 3-phenyl-7-hydroxy-6-arylazopyrazolo[1,5-a]pyrimid-5-ones 5. The resulting arylazo dyes (5) were refluxed in phosphorus oxychloride to give 3-phenyl-5,7-dichloro-6-arylazo-pyrazolo[1,5-a]pyrimidines 6 , which subsequently reacted with refluxing morpholine and piperidine to yield 3-phenyl-5,7-bis(morpholino and piperidino)-6-aryiazopyrazolo[1,5-a]pyrimidines 7. The arylazo dyes 5 and 7 were applied to polyester fibres as disperse dyes and the arylazo dyes 6 were applied to polyamide fibres as disperse reactive dyes. The spectral and dyeing properties of the dyes were studied.