1H Nmr stuctural analysis of N3′-dialkylaminoethyl derivatives from azabicyclospirohydantoins

Based on the data from ¹H nmr spectra, the structure and spatial conformation of the N₃′-β-dimethyl and diethylaminoethyl derivatives from 3-alkyl-3-azabicyclo[3.2.1]octane-8-spiro-5′-hydantoins and 3-alkyl-3-azabicyclo[3.3.1]nonane-9-spiro-5′-hydantoins are established. The monosubstitution on the imide nitrogen atom has also been confirmed.     

Diels-alder adducts of a spirocyclopentenotriazoloazodienophile. Assignment of their 1H and 13C NMR spectra

1-Phenyl-cyclopenteno[1,2-d]-1,2,3-rriazolo-5-spiro-4′-[perhydropyrazolino-3′,5′-dione] (5) afforded in situ, by oxidation with lead tetraacetate, the corresponding cyclopentenotriazolo-spiropyrazolodione 6 , which was trapped with dienes giving the hetero-Diels-Alder adducts 10–12 in good yields. The Diels-Alder reactions were examined on the basis of AM1 MO calculations. Total assignment of the ¹H- and ¹³C-nmr chemical shifts as well as the relative configuration of these adducts was accomplished with the help of 2D (¹H-¹H COSY, ¹H -¹ H NOESY, ¹H-¹³C XHCORR, ¹H-¹³C COLOC) and NOE difference spectroscopy. The structures of compounds 11a and 11b were also examined by molecular modeling.     

13C-Nmr spectra of anhydro-3-mercapto-5-pyrazinyl-1,2,4-triazolium hydroxides

The complete assignment of the ¹³C-nmr spectra of some anhydro-3-mercapto-5-pyrazinyl-1,2,4-triazolium hydroxides (1) is reported. For purposes of comparison the spectra of some isomeric triazole-3-thiones ( 2 ) are also reported. Positions C-3 and C-5 of the triazole ring and 2′ of the pyrazine moiety were found to be characteristic of each group of compounds.     

Synthesis and structural study of cyclopentane,indene and fluorene spiro-derivatives

The synthesis of three pharmacologically interesting series of cyclopentane, indene-2 and fluorine-9-spiro-5′-oxazolidine-2′, 4′-dione is described. Based on the data from ¹H and ¹³C nmr spectra, the main conformational features of the above mentioned compounds is established.     

Chemistry of the phenoxathiins and isosterically related heterocycles. XII. Synthesis of diazaphenoxathiin analogs: 1,9-Diazaphenoxathiin and 1,7-diazaphenoxathiin

The synthesis of the first diazaphenoxathiins, 1,9-diazaphenoxathiin and 1,7-diazaphenoxathiin, are described. Complete assignments are made for the ¹³C-nmr spectra of these compounds based on additivity correlation and ¹H-¹³C spin-coupling constants. The isolation and confirmation of the structure of 2-[2′(-3′-nitropyridylthio)]-3-[2″-(3″-nitropyridyloxy)] pyridine using ¹³C-nmr and appropriate model compounds is also discussed. A preliminary evaluation of spontaneous motor depression in mice showed a substantial difference between the observed activities of the two diazaphenoxathiins reported. The possibility of the observed difference being associated with the relative positions of the annular aza-substitutions is discussed.     

1H Nmr structural analysis of azabicyclospirohydantoins

Based on the data from ¹H nmr spectra, the structure and spatial configuration of the ahove mentioned hydantoins are established. In the 3-alkyl-3-azabicyelo[3.3.f ]nonane-9-spiro-5′-hydantoins analyzed, we confirm the chair-chair configuration and the presence of only one stereoisomer at the spiro carbon atom (with the C₄′=() group axial with regard to the piperidine ring). In the 3,7-dialkyl-3,7-diazabieyclo[3.3.1 ]nonane-9-spiro-5′-hydantoins analyzed, we also confirm the chair-chair configuration and we calculate the percentage of the two stereoisomers when they exist.     

Mass spectra of azabicyclospirohydantoins

The mass spectra of some N-substituted nortropane and granataninespirohydantoins are compared with those of N-substituted 3-azabicyclo[3.2.1]octane-8-spiro-, 3-azabicyclo[3.3.1]nonane-9-spiro-, 8-azabicyclo-[4.3.1]decane-10-spiro- and 3,7-diazabicyclo[3.3.1]nonane-9-spiro-5′-hydantoins. Mass spectra data of monothio- and dithio-tropanespirohydantoins are also included. Mass fragmentation and structure relationships of these molecules have been established.     

The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 4 . Benzo[f]thieno[2′,3′:4,5]thieno[2,3-c]quinoline and Benzo[h]thieno[2′,3′:4,5]thieno[2,3-c]quinoline and the total assignment of their 1H- and 13C-NMR spectra

The synthesis of two novel polycyclic heterocyclic ring systems via photocyclization are reported. These are benzo[f]thieno[2′,3′:4,5]thieno[2,3-c]quinoline and benzo[A]thieno-[2′,3′:4,5]thieno[2,3-c]quinoline. The total assignment of their ¹H- and ¹³C-nmr spectra was determined by utilizing two-dimensional nmr spectroscopic methods.     

Synthesis and 1H-, 13C-NMR analysis of some substituted 1,2,3,4-tetrahydroisoquinolines

Synthesis and ¹H-, ¹³C-nmr analysis of some substituted 3-phenyl-1,2,3,4-tetrahydroisoquinolines are reported. Spectroscopy assignments of hydrogen and carbon resonances were made on the basis of standard chemical shift theory, comparison with reference compounds, attached proton test and fully coupled ¹³C-nmr spectra. Data showed that at room temperature two conformers predominated for the 1,3-disubstituted and 1,2,3-trisubstituted isoquinolines.     

Preparation and some spectral properties of benzo-fused 1,4-dimethyl-2(1H)-quinolinones

The preparation of the angular and linear isomers of benzo-fused 1,4-dimethyl-2(1H)-quinolinones 3a–5a and their spectral data including ¹³C-nmr data are reported. Structural difference among 3a–5a is confirmed from the proximity effect in ¹H- and ¹³C-nmr data and from the uv spectral pattern.     

1-Methylphenanthro[3,4-b]thiophene: Determination of the tertiary structure in solution and in the crystalline state by NMR spectroscopy and X-ray diffraction

1-Methylphenanthro[3,4-b]thiophene was prepared by the photocyclization of 1-(4′-methyl-2′-thienyl)-2-(2″-naphthyl)ethene. The ¹H and ¹³C-nmr spectra were assigned using two-dimensional ¹H/¹³C heteronuclear chemical shift correlation and relayed coherence transfer (RELAY) experiments. From nuclear Overhauser difference spectra, the H11-C1 methyl-H intramolecular distance was determined to be 2.10 Å. The molecule crystallized from chloroform in the monoclinic system, space group P2₁/c. A total of 3536 unique reflections were measured and the structure was solved by direct methods and refined to a final R = 0.049. The molecule is helical with both chiral forms observed in the crystal. The H11-C1 methyl-H distance in the crystal was 2.12(3)Å in excellent agreement with the distance measured in solution by NOE techniques.     

On triazoles. VII Synthesis of novel tri- and tetracyclic ring systems

The ring-closure of the 5-amino-1-(2-aminophenyl)-3-methylthio-1H-1,2,4-triazole derivatives 3 and 4 with different simple and cyclic C₁ components lead to the formation of 1,2,4-triazolo[1,5-α]-1,3,5-benzotriazepines 5–6 , their 4,5-dihydro- 7 , different 5-spiro-homocyclic- 8–13 , and 5-spiro-heterocyclic- 14-15 analogues. The structure of the compounds obtained was proved with the use of their ir, uv, ¹H-nmr and ¹³C-nmr spectra.     

Five-membered 2,3-dioxoheterocycles: LVIII. Reaction of methyl 1-Aryl-3-aroyl-4,5-dioxo-4,5-dihydro-1H-pyrrol-2-carboxylates with substituted 1-methyl-3,4-dihydroisoquinolines. New approach to the synthesis of steroid 13-azaanalogs

Methyl 1-aryl-3-aroyl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates reacted with substituted 1-methyl-3,4-dihydroisoquinolines with the formation of substituted 3-oxo-2,3,5,6-tetra-hydropyrrolo[2,1-a]-isoquinoline-2-spiro-2′-(1-aryl-3-aroyl-4-hydroxy-5-oxo-2,5-dihydro-1H-pyrroles). A new approach was developed to the synthesis of 13-azagonanes, substituted benzo[f]pyrrolo[2,1-a]isoquinoline-9-spiro-2′-pyrroles.     

Nmr spectroscopic studies on the tautomerism in tenuazonic acid analogs

Nmr spectra of structural analogs of tenuazonic acid such as 3-acetyltetramic acid, 3-acetyltetronic acid, 3-acetylthiotetronic acid and others were investigated for elucidation of the tautomeric structures. These compounds have completely enolized β,β′-triketone systems, and the position of the nmr signals for the enolic proton shows that the strength of their intramolecular hydrogen-bonding is weaker than those of acyclic β,β′-triketones and six-membered cyclic triketones. The assignment was made for nmr signals split by the difference of the diamagnetic anisotropic effect in each tautomers. The percentages of each of the tautomers were calculated from the intensities of the corresponding nmr signals. The results were confirmed by means of ¹³C-nmr spectroscopy.     

1H nmr structural analysis of azabicyclospirohydantoins

The structure and spatial conformation of 3-alkyl-3-azabicyclo[3.2.1]octane-8-spiro-5′-hydantoins and 8-alkyl-8-azabicyclo[4.3.1]decane-10-spiro-5-hydantoins has been determined on the basis of the data from ¹H nmr. The chair conformation of the piperidine ring and the presence of only one stereoisomer at the spiro carbon atom are corroborated. All these facts have been confirmed by x-ray diffraction methods (2).     

On triazoles. V. Synthesis of 1- and 2-R1-3-R2,R3-amino-5-amino-1,2,4-triazoles

The correct isomeric and tautomeric structure of different 1- and 2-R¹-3-R²,R³-amino-5-amino-1,2,4-triazole derivatives prepared from the corresponding N-cyano-N'-R²,R³-S-methyl-isothioureas and the corresponding hydrazines was proved with the help of their ir, uv, ¹H-nmr and ¹³C-nmr spectra as well as the uv spectra of the Schiff bases of an isomeric pair.     

Synthesis of 2H-pyrano[2,3-b]quinolines. Part II. Preparation and 1H-nmr investigations of 4-hydroxy-2-methyl-3,4-dihydro-2H-pyrano[2,3-b]quinolines

Diastereoisomers of 4-hydroxy-2-methyl-3,4-dihydro-2H-pyrano[2,3-b]quinolines 8 and 9 were synthesized starting from the appropriate 2-chloroquinoline-3-carboxaldehydes 1. The relative configuration of the 1,3-diol intermediates 4 and 5 was determined on the basis of the ¹³C-nmr spectra of their acetonides. The relative stereochemistry of title compounds was confirmed by using homonuclear NOE and selective decoupling experiments, as well as by analysis of the coupling patterns observed in their ¹H-nmr spectra.     

Configurational assignments of oximes derived from 5-formyl and 5-acyl-1,2,4-triazines

The configuration of (3-substituted)-1,2,4-triazin-5-ylcarbaldoximes and (3-substituted)alkyl-1,2,4-triazin-5-ylketoximes was determined by means of ¹H-nmr, ¹³C-nmr, ¹⁵N-nmr and homonuclear NOE-difference spec-troscopy. Oximes resulting from reaction of 1,2,4-triazines with nitroalkanes were found to be either pure E-isomers or E/Z-mixtures with the amount of E-isomer greatly predominating. Detailed ¹³C-nmr data of the oximes investigated are presented.     

Synthesis and spectral properties of methyl 5-[(o-, m-, and p-R)-phenoxy]-2-benzimidazolecarbamate

The preparation of eleven novel methyl 5-[(o-, m-, p-R)-phenoxy-2-benzimidazolecarbamates with possible pharmacological activity as anthelmintics is described. The structure of all products was corroborated by ir, ¹H-nmr, ¹³C-nmr and mass spectra.     

The assignment of the 1H-NMR and 13C-NMR spectra of 5H-dibenz[b,f]azepine and 10,11-dihydro-5H-dibenz[b,f]azepine

The total assignments of the ¹H-nmr and ¹³C-nmr spectra of 5H-dibenz[b,f]azepine [1] and 10,11-dihydro-5H-dibenz[b,f]azepine ( 2 ) have been made based on comparison with the corresponding 4,6-dideuterated derivatives 3 , and 4 . These compounds were prepared via repeated lithiations and subsequent deuterations of 1 and 2 .