SCHWEFELDIIMIDE MIT SILYL-, GERMYL-, STANNYL- UND PHOSPHINYL-HETEROSUBSTITUENTEN. SYNTHESE UND NMR-SPEKTROSKOPISCHE CHARAKTERISIERUNG

Abstract

Reactions of the salts K₂SN₂ and K[(NSN)R] (R = ′Bu, SiMe₃ and P′Bu₂) with organoelement chlorides R′R′ěl have been used to prepare four series of model sulfur diimides: R′R″E(NSN)ER″R′, ′Bu(NSN)ER″R′, Me₃Si(NSN)E″R′ and ^tBu₂P(NSN)ER″R′, respectively (E = C, Si, Ge, Sn; R′ and R″ = alkyl or aryl group). All compounds have been characterized by ′H and ¹³C NMR and—if possible—by ³¹P, ²⁹Si and ¹¹⁹Sn NMR spectroscopy. The configuration (Z or E) of the substituents R and E″R′ has been assigned in several cases using ^tBu(NSN)^tBu (1) as a reference. The E,Z assignment of ¹H, ¹³C and ¹⁵N nuclei in 1 is based on selectively ¹H-decoupled refocused INEPT ¹⁵N NMR and two-dimensional (2D) ¹³C/¹H heteronuclear shift correlations. The sulfur diimides under study are in general fluxional in solution.     

Nitropyrazoles

The structures of substitutedN-aminonitropyrazoles and 1- and 2-amino-4-nitro-1,2,3-triazoles as well as the site of protonation of 1-aminopyrazole were determined based on the¹H,¹³C, and¹⁵N (¹⁴N) NMR spectra. The¹³C NMR spectra were recorded under conditions of¹³C-{¹H,¹⁴N} triple resonance. Effects of substituents in the pyrazole ring on the¹³C and¹⁴N chemical shifts were studied. The¹³C,¹H and¹⁵N,¹H spin-spin coupling constants, obtained using techniques of [¹H]¹³C and [¹H]¹⁵N polarization transfer (SPT, INEPT), were measured, fully assigned, and discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2181–2186, November, 1995.For Part 8, see Ref. 1.     

NMR spectroscopic study of the (Z)/(E)-isomerism of 1-aryl-3-arylamino-2-propen-1-ones in solution and in the crystalline state

Summary ¹H,¹³C, and CP/MAS¹³C NMR spectra of sixp-substituted 1-aryl-3-arylamino-2-propen-1-ones in solution and in the solid state are reported and discussed. In the proteon-accepting solvent dimethylsulfoxide, electronegative substituents shift the isomeric equilibrium to the (E)-isomer. Bulky substituents promote crystallization of the (Z)-form.

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NMR-Spektroskopische Untersuchung der (Z)/(E)-Isomerie von 1-Aryl-3-arylamino-2-propen-1-onen in Lösung und im Kristallzustand (Kurze Mitt.)

Zusammenfassung ¹H-,¹³C- und CP/MAS-¹³C-NMR Spektren von sechsp-substituierten 1-Aryl-3-arylamino-2-propen-1-onen in gelöstem und festem Zustand werden berichtet und diskutiert. In protonenakzeptierendem Dimethylsulfoxid verschieben elektronegative Substituenten das Gleichgewicht zum (E)-Isomer. Große Substituenten begünstigen die Kristallisation in der (Z)-Form.

     

Evidence of C non-covalent isotope effects obtained by quantitative C nuclear magnetic resonance spectroscopy at natural abundance during normal phase liquid chromatography

Quantitative isotopic ¹³C NMR at natural abundance has been used to determine the site-by-site ¹³C/¹²C ratios in vanillin and a number of related compounds eluted from silica gel chromatography columns under similar conditions. Head-to-tail isotope fractionation is observed in all compounds at the majority of carbon positions. Furthermore, the site-specific isotope deviations show signatures characteristic of the position and functionality of the substituents present. The observed effects are more complex than would be obtained by simply summing the individual effects. Such detail is hidden when only the global ¹³C content is measured by mass spectrometry. In particular, carbon positions within the aromatic ring are found to show site-specific isotope fractionation between the solute and the stationary phase. These interactions, defined as non-covalent isotope effects, can be normal or inverse and vary with the substitution pattern present.     

13C, 15N and 113Cd NMR and Molecular Orbital Studies of Novel Bile Acid N-(2-aminoethyl)amides and Their Cd2+-complexes

Lithocholic acid N-(2-aminoethyl)amide (1) and deoxycholic acid N-(2-aminoethyl)amide(2) have been prepared and characterized by¹H, ¹³C and ¹⁵N NMR. The accurate molecular masses of 1 and 2 have been determined by ESI MS. The formation of the Cd²⁺-complexes (1+Cd and 2+Cd) in CD₃OD solution have been detected by ¹H,¹³C, ¹⁵N and ¹¹³Cd NMR. The ¹³C NMR chemical shift assignments of 1 and 2 and their Cd²⁺-complexes are based on DEPT-135 and z-GS ¹H,¹³C HMQC experiments as well as comparison with the assignments of the related structures. The ¹⁵N NMR chemical shiftassignments of the ligands and theirCd²⁺-complexes are based on z-GS¹H,¹⁵N HMBC experiments. ¹³C NMR chemical shift differences between 1and its 1:1 Cd²⁺-complex based on ab initiocalculations at Hartree-Fock SCI-PCM level using3-21G(d) basis set are in agreement with theexperimental shift changes observed onCd²⁺-complexation.     

Mercury(II) cyanide complexes with alkyldiamines: solid-state/solution NMR,computational, and antimicrobial studies

Mercury cyanide complexes of alkyldiamines (1–6), [Hg(L)(CN)₂] (where L?=?en (1,2-diaminoethane), pn (1,3-diaminopropane), N-Me-en, N, N′-Me₂-en, N, N′-Et₂-en, and N, N′-ipr₂-en), have been synthesized and characterized by elemental analysis, IR, ¹³C, and ¹⁵N solution NMR in DMSO-d₆, as well as ¹³C, ¹⁵N, and ¹⁹⁹Hg solid-state NMR spectroscopy. Complexes 1 and 2 have been studied computationally, built and optimized by GAUSSIAN03 using DFT at B3LYP level with LanL2DZ basis set. Binding modes of en and bn (where bn?=?1,4-diaminobutane) toward Hg(CN)₂ are completely different. Complexes with en and pn show chelating binding to Hg(II), while bn behaves as a bridging ligand to form a polymeric structure, [Hg(CN)₂-bn]_∞ [B.A. Al-Maythalony, M. Fettouhi, M.I.M. Wazeer, A.A. Isab. Inorg. Chem. Commun., 12, 540 (2009).]. The solution ¹³C NMR of the complexes demonstrates a slight shift of the ?C≡N (0.9 to 2?ppm) and ?C–NH₂ (0.25 to 6?ppm) carbon resonances, while the other resonances are relatively unaffected. ¹⁵N labeling studies have shown involvement of alkyldiamine ligands in coordination to the metal. The principal components of the ¹³C, ¹⁵N, and ¹⁹⁹Hg shielding tensors have been determined from solid-state NMR data. Antimicrobial activity studies show that the complexes exhibit higher antibacterial activities toward various microorganisms than Hg(CN)₂.     

Substituent effects of phosphonate groups electronic repartition of π-conjugated ferrocene analogues of stilbene

The synthesis of para-substituted ferrocene analogues of stilbene was performed by using the Heck reaction, starting from vinylferrocene. The variation of the electronic density of these compounds with the electronic withdrawing strength of the substituents was studied using ¹³C NMR spectroscopy, absorption spectra and cyclic voltammetry. The correlation of Hammett constants with the redox properties of the substituted compounds using Nagy's method allowed us to revisit the determination of the Hammett constants of diethyl phosphonate ester and phosphonic acid substituents. Our measurements were in agreement with the literature except for the diethyl phosphonate group.     

The increment scheme for the prediction of13C NMR chemical shifts in polychlorinated dibenzo-p-dioxins

A topological method for the calculation of¹³C NMR chemical shifts was developed for polychlorinated dibenzo-p-dioxins (PCDD). Based on previous results for polychlorinated benzenes and polyhydroxybenzenes, the collective influence of the substituents on carbon chemical shifts is presented as the sum of two-particle increments. The increments only of two new monosubstituted graphs have to be added to those known for PCDD spectra: 1-Cl-DD and 2-Cl-DD. All structural situations in the¹³C NMR chemical shifts of the whole class of 75 PCDD can be covered with a few model compounds. The coefficients of the increment scheme are independent of the change of CDCl₃ for acetone-d₆, so it may be a new reliable criterion for recognizing PCDD by¹³C NMR, in spite of the close resemblance of NMR spectra of aromatic compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 280–284, February, 1995.     

Structures of polychlorinated naphthalenes and oxynaphthalenes and their13C NMR chemical shifts

The increment scheme for calculating chemical shifts of polysubstituted naphthalenes is based on 1- and 2-substituted heterosubgraphs which describe the main part of the substituent effect. The influence of several substituents on¹³C NMR chemical shifts have been described by two-particle increments corresponding to 1,2- and 2,3-ortho-disubstituted heterosubgraphs (the steric interaction of substituents in the same ring) and also to 1,4-conjugation of the substituents. Conjugation of two benzene rings required the introduction of a two-particle 1,8-heterosubgraph to the increment system. The systems of two-particle increments were obtained for polychlorinated naphthalenes, oxynaphthalenes, and polychlorinated oxynaphthalenes. Predicted¹³C NMR spectra of polychlorinated naphthalenes not included in the increment analysis proved to be in good agreement with independent measurements.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp.625–628, April, 1994.     

The Reaction Activity of Aromatic Carbonyl Compounds with Diphenylphosphine Oxide Studied by 31P NMR

Abstract

A series of α-hydroxyphosphine oxides were prepared by the reactions of diphenylphosphine oxide and aromatic carbonyl compounds and characterized by ¹H NMR, ¹³C NMR, ³¹P NMR, FT-IR, ESI-MS, and HR-MS spectra. The reaction rates and experimental conditions of aromatic aldehydes and aromatic ketones were obviously different due to the activity of their carbonyls. The different substituents of the aromatic aldehydes affected the reaction rate too, and the quantitative reactivity of their substituent conformed to the Hammett equation. The results were confirmed by ³¹P NMR spectroscopy.     

Electron density distributions in substituted 2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-dienes studied by NMR spectroscopy

The signals in the¹³C NMR spectra of 2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-dienes (R¹=R²=H, Me,cyclo-C₃H₅, SiMe₃, SnMe₃, R¹=Me, R²=H, Cl) were completely assigned using 2D NMR spectroscopy. The pattern of the variation of the chemical shifts in the¹³C NMR spectra indicates that the effects of substituents R¹ and R² on the heterocycle and on the phenyl groups are of inductive rather than mesomeric origin and include the direct through-space polarization of bonds (field effect). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1962–1965, November, 1997.     

A 13C, 15N and 77Se NMR Study of Some Diseleno Sulfonamides

¹³C, ¹⁵N and ⁷⁷Se NMR data are reported for ten title compounds. Some linear correlations of selenium, nitrogen and carbon chemical shifts values are described. A number of one- and two- bond ⁷⁷Se-¹³C coupling constants values are also given.     

Structural Refinement of Carbimazole by NMR Crystallography

The characterization of the three-dimensional structure of solids is of major importance, especially in the pharmaceutical field. In the present work, NMR crystallography methods are applied with the aim to refine the crystal structure of carbimazole, an active pharmaceutical ingredient used for the treatment of hyperthyroidism and Grave’s disease. Starting from previously reported X-ray diffraction data, two refined structures were obtained by geometry optimization methods. Experimental ¹H and ¹³C isotropic chemical shift measured by the suitable ¹H and ¹³C high-resolution solid state NMR techniques were compared with DFT-GIPAW calculated values, allowing the quality of the obtained structure to be experimentally checked. The refined structure was further validated through the analysis of ¹H-¹H and ¹H-¹³C 2D NMR correlation experiments. The final structure differs from that previously obtained from X-ray diffraction data mostly for the position of hydrogen atoms.     

Cyclohexanone Dimethyl Acetals: A 13C NMR, Thermodynamic, and Ab Initio Study

The spatial structures of a number of mono- and disubstituted 1,1-dimethoxycyclohexanes (cyclohexanone dimethyl acetals) were studied by ¹³C NMR spectroscopy. In the monosubstituted acetals, substituents (Me, Et, i-Pr, and MeO) on C-2 are axially oriented, contrary to their normal, equatorial orientation on C-3 and C-4. Besides the spectroscopic study, the relative thermodynamic stabilities of the cis-trans isomers of a few 2,X-dialkyl (X = 3, 4, 5, or 6) derivatives of the parent cyclohexanone dimethyl acetal were determined by acid-catalyzed chemical equilibration in MeOH solution. In the most stable isomeric form, the 2-substituent is axial and the other equatorial. In the less stable isomer, both substituents are equatorial, excluding the cis-2,6-dimethyl derivative, where the ¹³C NMR shift data point to a predominance of the diaxial form. In general, the enthalpy difference between the isomeric forms is ca. 9 kJ mol^–1, while the entropy term favors the less stable isomer by 4 to 16 J K^–1 mol^–1. In the 2,6-dimethyl derivatives, however, the trans form is favored by only 0.8 kJ mol^–1 in G _m at 298.15 K. The main findings of the experimental work are in good agreement with ab initio calculations.     

Isomerization of substituted tricyclic 4,5-dihydropyrazoles

Summary The acid and base catalyzed isomerization of some tricyclic 2-pyrazolines with N-Carbamoyl-,N-thiocarbamoyl-and N-phenyl substituents was investigated. Starting fromcis ortrans 3-H, 3a-H diastereomers, equilibrium mixtures ofcis andtrans diastereomers were prepared which were separated and subsequently studied by¹H NMR and¹³C NMR spectroscopy. A mechanism for the isomerization of the pyrazolines is suggested, supported by a deuterium exchange at C-3a.

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Isomerisierung von einigen substituierten 4,5-Dihydropyrazolen

Zusammenfassung Die Isomerisierung einiger tricyclischer 2-Pyrazoline mit N-Carbamoyl-, N-Thiocarbamoyl-und N-Phenyl-substituenten unter saurer und basischer Katalyse wurde untersucht. Ausgehend von dencis odertrans 3-H,3a-H-Diastereomeren wurdencis- undtrans Gleichgewichtsgemische gewonnen, die getrennt und durch¹H- und¹³C-NMR-Spektroskopie untersucht wurden. Ein Mechanismus für die Isomerisierung von Pyrazolinen wird vorgeschlagen, der durch den Deuteriumaustausch in Position 3a-C unterstützt wird.

     

Phosphorus Derivatives of Natural Lactones. Synthesis of New Grosshemin Dialkylphosphonates

New phosphorus-containing derivatives of grosshemin were synthesized in 68-70% yield by reacting this guaianolide with dialkylphosphites. Their structures were established by IR, PMR, ¹³C NMR, and ³¹P NMR spectroscopies and two-dimensional ¹H-¹H NMR spectroscopy (COSY). The reaction of grosshemin with dialkylphosphites was found to be highly stereoselective.     

Stereochemicai study of 7-aryl-1,7,8,8a-tetrahydro-3(2H)indolizinones by1H and13C NMR

Stereochemistry of 7-aryl-1,7,8,8a-tetrahydro-3(2H)-indolizinones was studied by¹H and¹³C NMR. Complete assignment of¹H NMR signals and analysis of¹H-¹H coupling constants were performed using the iterative PANIC program. Values of³ J _6,7,³ J _7,8endo, and⁴ J _5,7 allow one to unambiguously identify the correspondingexo- andendo-stereoisomers. For stereoisomers with exo-orientation of H(7), complete assignment of¹³C NMR signals was performed on the basis of analysis of the¹³C-¹H coupling constants using two dimensional heteronuclear shift-correlating spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 591–593, March, 1996.     

Rapid and novel discrimination and quantification of oleanolic and ursolic acids in complex plant extracts using two-dimensional nuclear magnetic resonance spectroscopy—Comparison with HPLC methods

A novel strategy for NMR analysis of mixtures of oleanolic and ursolic acids that occur in natural products is described. These important phytochemicals have similar structure and their discrimination and quantification is rather difficult. We report herein the combined use of proton-carbon heteronuclear single-quantum coherence (¹H-¹³C HSQC) and proton-carbon heteronuclear multiple-bond correlation (¹H-¹³C HMBC) NMR spectroscopy, in the identification and quantitation of oleanolic acid (OA) and ursolic acid (UA)in plant extracts of the Lamiaceae and Oleaceae family. The combination of ¹H-¹³C HSQC and ¹H-¹³C HMBC techniques allows the connection of the proton and carbon-13 spins across the molecular backbone resulting in the identification and, thus, discrimination of oleanolic and ursolic acid without resorting to physicochemical separation of the components. The quantitative results provided by 2D ¹H-¹³C HSQC NMR data were obtained within a short period of time (∼14 min) and are in excellent agreement with those obtained by HPLC, which support the efficiency of the suggested methodology.     

Synthesis and Stereochemistry of New N-Substituted Cytisine Derivatives

A series of new N-substituted cytisine derivatives was synthesized. The ¹ H and ¹³ C NMR spectra of certain compounds exhibit a doubled set of signals. This is explained by formation of diastereomeric pairs in compounds containing an asymmetric center in the substituents. The signal splitting in -COHC=CHCO ₂ H and HC=O (formyl) derivatives is explained by the existence of Z and E invertomers. Their stereochemical features are discussed. Amide conjugation is confirmed by temperature experiments.     

Synthese von 5-Dialkylamino-1,2-oxazolen aus N,N-Dialkyl-β-amino-α,β,γ,δ-ungesättigten Thioamiden

Summary 3-Amino-2,4-pentadienthioamides, which were obtained from 6-dialkylamino-2H-thiopyrane-4(3H)iminium halides by alkali hydrolysis, react with hydroxylamine hydrochloride in a [C-C-C] + [N-O]-addition to give selectively 5-amino-3-alkenyl-1,2-oxazoles. These oxazoles have been identified by¹³C and¹H NMR spectroscopic analysis. The configuration of these compounds was established on the basis of the coupling constants and 2D-NOESY-experiments. The position of the substituents has been determined by analysis of the fragmentation pattern.

Herrn Prof. Dr. Robert Ott zum 70. Geburtstag gewidmet