Nitrogen NMR sudies of some 15N labelled sydnones and related stuctures

¹⁵N NMR studies on some signly labelled sydnones, N-acetylsydonimines and their hydrochlorides, as well as those on some sydnonimine hydrochlorides, show that in each case protonation takes place at the exocyclic moiety, \documentclass{article}\pagestyle{empty}\begin{document}$ - {\rm O}^ \ominus - \mathop {\rm N}\limits^ \ominus {\rm COCH}_3 \,{\rm or}\, - \mathop {{\rm NH}}\limits^ \ominus $\end{document}, respectively. Complete assignments of the nitrogen chemical shifts are possible for the labelled compounds, including the isomeric structures of N-alkyl–N-cyanomethyl–N–nitrosoamines to which, unstable, free sydnonimines are converted.     

Synthesis of sydnonimine derivatives as potential trypanocidal agents

N‐(p‐Nitrophenoxy)carbonyl‐3‐morpholino‐sydnonimine (NCMS) has been prepared from 3‐morpholinosydnonimine hydrochloride. Using the Griess assay and the superoxide‐mediated reduction of ferricytochrome c, the nitric oxide (NO?) and superoxide anion (O₂?^‐) ‐ releasing properties in phosphate buffer pH 7.4 of this novel peroxynitrite donor was studied and compared with the known 3‐morpholino‐sydnonimine (SIN‐1). From compound NCMS, a series of N‐substituted sydnonimine derivatives were easily prepared that contain purine or melaminophenyl groups which specify a recognition by a trypanosomal purine transporter. The ability of these new sydnonimines to inhibit the uptake of [2³H]adenosine on Trypanosoma equiperdum was studied.     

Selenoacetalyzation of 4‐Formylpyrazoles in the Presence of Trimethylchlorosilane

The reaction of 3,5‐dimethyl‐4‐formylpyrazoles, bearing various substituents at N‐1 atom, with propane‐1,3‐diselenol and 2‐hydroxypropane‐1,3‐diselenol in the presence of ТМSCl proceeds without heating to chemoselectively give hitherto unknown 2‐(pyrazol‐4‐yl)‐1,3‐diselenane hydrochlorides in high yields. The latter are easily transformed to the corresponding free bases—2‐(pyrazol‐4‐yl)‐1,3‐diselenanes. The ¹⁵N chemical shifts of the pyrazole ring in 2‐(pyrazol‐4‐yl)‐1,3‐diselenanes obtained by 2D HMBC‐gp (¹⁵N‐¹H) technique are indicative of the N‐2 atom protonation in hydrochlorides.     

Comparaison des effets α-methyle sur des sites 13C et 15N a l'aide du modele topologique (α-Me) par difference lineaire (DARC-PULFO)

The extension to ¹⁵N NMR of the model by linear difference previously proposed for (α-Me.) ¹³C shifts gathers in an unifying treatment the different behaviours observed for (α-Me.) shifts in ¹⁵M and ¹³C of, aliphatic amines, hydrochlorides and alkanes.     

The conformational dependence of 15n13c spin spin coupling constants

2-Azabicyclo(2.2.2)octan-3-One 1, N-isopropylpivaloylamide 2 and 4-azatricyclo(4.3.1.1^3,8)undecan-5-one 3 have been prepared with a ¹⁵N label. The amides were reduced to the corresponding amines 2-azabicy-clo(2.2.2)octane 4, N-isopropyl-N-neopentylamine 5 and 4-azatricyclo(4.3.1.1^3,8)undecane 6. The ¹³C spectra of these compounds and their hydrochlorides were measured and the ¹⁵N¹³C spin coupling constants interpreted in terms of their conformational dependence.     

Nitrogen-containing organosilicon compounds. 151. Synthesis,NMR spectra,and biological activity of hetarylaminoalkylsiloxanes and their hydrochlorides and methiodides

Hetarylaminoalkylsiloxanes and their hydrochlorides and methiodides were synthesized. Their neurotropic, antitumorigenic, and antimicrobial properties were studied. It was established that the character of the heteroring, the number of siloxy groups, and the length of the methylene chain between the nitrogen and silicon atoms in the molecule affect the biological activity. It is shown that the changes in the chemical shifts in the ¹³C, ¹⁵N, ¹⁷O, and ²⁹Si NMR spectra of the synthesized compounds are determined chiefly by the presence of siloxy substituents, i.e., the effects in the Si-O-Si fragment prevail.See [1] for communication 150.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1653–1664, December, 1991.     

15N NMR spectroscopy. 30—structure/shift relationships of oligopeptides and copolypeptides,including gramicidin S

The ¹⁵N NMR spectra of various oligopeptide derivatives of the Z? X? Y? Y? OMe structure, where X and Y are variable amino acids and Z is the benzyloxycarbonyl group, were measured in several protic and aprotic solvents. The shift difference of the ¹⁵N of the Y? Y and X? Y bond (neighbouring residue effect) is discussed with respect to the nature of X and Y with respect to the solvent. Oligopeptides of the Z? X? Y? Y? OH and n?H₃? X? Y? Y? OMe structures were compared with the Z-pëptide esters to investigate the spectroscopic influence of the protecting groups. The methyl ester hydrochlorides of the 25 most common amino acids were measured in water and DMSO to elucidate the solvent dependence of the substituent effects. Moreover, the methyl ester hydrochlorides were compared with Z-amino acids and N-acetyl-amino acid methyl esters in DMSO to establish whether the substituent effects depend on the nature of the amino acid derivatives. In this connection the assignments of the serine, threonine and glycine signals are discussed with respect to silk proteins. Furthermore, the assignments of the signals of copolypeptides by comparison with oligo- and homo-polypeptides are discussed. Finally, it was demonstrated that intramolecular H bonds cause downfied shifts of 7–10 ppm of the acceptor amide groups.     

Determination of rotational barriers of carbon?carbon bonds in 2-arylpiperidines

Carbon-carbon sp³-sp² rotational barriers of 3,3-dimethyl-2-(3,4,5-trimethoxyphenyl)-4-piperidones and their ethylene ketals have been evaluated using nmr techniques. The conformation of 1 hydrochloride has been studied by NOE determinations. Values found for the hydrochlorides of the title compounds are discussed in terms of equilibria with free bases and nitrogen inversion.     

Organosilicon synthesis of isocyanates: IV. Synthesis of isocyanates from aliphatic and alkylaromatic amino acid esters

Treatment of an alcoholic suspension of amino acids with trimethylchlorosilane yielded phenylglycine, valine, β-phenylalanine, and homovaline ester hydrochlorides. Their saccharin-catalyzed silylation with hexamethyldisilazane proceeds quantitatively and involves only one proton of the amino group. The best conversion of the amino acid esters to the corresponding isocyanates was achieved by phosgene treatment of their monosilyl urethanes, rather than of the silylated amino esters. Monosilyl urethanes are formed quantitatively by treatment of the amino acid ester hydrochlorides with the hexamethyldisilazane-CO₂ system. The ¹H NMR spectra show that monosilyl urethanes derived from α-and β-amino acid esters are characterized by intramolecular interaction of the silicon atom and the oxygen atom of the carboxy group.     

Reactions of N-substituted 3-azabicyclo[3.3.1]nonan-9-ones with N,N-, N,S-, and N,O-binucleophiles

Condensation of N-substituted 3-azabicyclo[3.3.1]nonan-9-ones with difunctional N,N-, N,S-, and N,O-centered nucleophiles (o-phenylenediamine, 1,2-diphenylethane-1,2-diamine, 2-aminobenzenethiol, cysteine, 2-aminophenol, serine) gave the corresponding spiro heterocyclic compounds fused at the C⁹ atom. Treatment of N-tert-butoxycarbonyl-substituted spiro compounds with anhydrous hydrogen chloride resulted in elimination of the tert-butoxycarbonyl group with formation of spiro[3-azabicyclo[3.3.1]nonane-9,2′-azole] hydrochlorides.     

Facile synthesis of novel 3-quinoxalinyl-1,5-benzodiazepines via ring transformation. Stable tautomers in the 1,5-benzodiazepin-2-one ring system

Novel 3-quinoxalinyl-1,5-benzodiazepines 4, 5, 6, 9, 10 were synthesized via the ring transformation of 3-(N,N-dimethylcarbamoyl)furo[2,3-b]quinoxaline hydrochloride ( 1 ). The 3-quinoxalinyl- 1 ,5-benzodiazepine hydrochlorides 4 and 6 are the tautomers of the N^1′-H (or N⁵-H) form and the C³-H form, respectively, which are stable in solid and solution. However, 4 (NH form) was found to be converted into 6 (C³-H form) by refluxing in acetic acid. The individual spectral evidences and different reactivity of these tautomers are described.     

Synthesis,NMR‐Spectroscopy,and Molecular Structure of a Phosphonyl Ene Diamine

First examples of ene diamines with a phosphonate function at the C=C double bond were obtained by the reaction of dialkyl H‐phosphonates with bis(N‐tert‐butyl)‐diimine derived from glyoxal, [1,4‐bis(tert‐butyl)‐1,4‐diaza‐1,3‐butadiene], and isolated as hydrochlorides. Preferentially the cis‐diamine is formed. The new phosphonates are characterized by multinuclear NMR spectroscopy(¹H, ¹³C, ³¹P). In addition the methyl ester 8a was characterized by ^14,15N NMR spectroscopy as well as by several 2D NMR techniques and single‐crystal X‐ray diffraction, unequivocally establishing the ene diamine structure. In the crystal dimers of the cations are formed by P–O ··· H–N hydrogen bonding.     

Synthesis,structural, conformational and biochemical study of some 3β-acyloxytropan-3α-carboxylic acid hydrochlorides

A series of 3β-acyloxytropan-3α-carboxylic acid hydrochlorides have been synthesized and studied by ¹H and ¹³C nmr spectroscopy, and the crystal structure of 3β-(3,4,5-trimethoxybenzoyloxy)tropan-3α-carboxylic acid hydrochloride 4c has been determined by X-ray diffraction. The compounds studied display in methanol-d₄ the same preferred conformation. The pyrrolidine and piperidine rings adopt a flattened N8 envelope and distorted chair conformation; puckered at N8 and flattened at C3 respectively with the N-substituent in equatorial position with respect to the piperidine ring. In all cases, there is only one mode (axial) of proton uptake at the piperidine nitrogen atom. These results are in close agreement with that found for compound 4c in the crystalline state. The inhibitory ability of the title compounds upon ³ H -GABA binding to sinaptosomal brain membranes is also reported.     

The synthesis and characterization of a poly(maleimide-ether) containing pendent thiophene rings

The preparation of a poly(maleimide-ether) containing pendent thiophene rings via the reaction of 2-(3-thienylmethyl)-1,3-N,N'-bis(3,4-dichloromaleimido) propane with 1,4-dihydroxybenzene is described. The novel 2-substituted-1,3-N,N'-bis(3,4-dichloromaleimido) propanes were obtained by allowing their corresponding diamine hydrochlorides to react with 3,4-dichloromaleic anhydride in acetic acid in the presence of sodium methoxide. The diamine hydrochlorides were prepared by the reduction of their respective diamides. The poly(maleimide-ether)s were fully characterized and ¹³C-NMR spectroscopy was used to confirm the microstructure of the materials. The properties of the thiophene substituted polymer are compared with model poly(maleimide-ether)s. Electrochemical studies indicated that the thiophene rings in the thiophene-substituted poly(maleimide-ether) were not electroactive. © 1992 John Wiley & Sons, Inc.     

Palladium‐catalyzed three‐component cyclization of 2‐bromocyclohex‐1‐enecarboxylic acids with carbon monoxide and arylhydrazines leading to 2‐anilinohydroisoindoline‐1,3‐diones

2‐Bromocyclohex‐1‐enecarboxylic acids are carbonylatively cyclized with arylhydrazines or their hydrochlorides in tetrahydrofuran at 120 °C under carbon monoxide pressure in the presence of a catalytic amount of PdCl₂ and 1,3‐bis(diphenylphosphino)propane along with Et₃N to give 2‐anilinohydroisoindoline‐1,3‐diones. Copyright © 2015 John Wiley & Sons, Ltd.     

1H and 13C NMR spectral analysis of some necines of toxic pyrrolizidine alkaloids

Summary The total assignment of the ¹H and ¹³C NMR spectra of the necines of toxic pyrrolizidine alkaloids (retronecine, heliotridine, crotanecine, otonecine), their hydrochlorides and their N-oxides has been performed. The characteristic chemical shift differences between retronecine and heliotridine, as well as the protonation and N-oxidation shift effects in NMR studies of necines at the corresponding position are proposed to be an additional assignment aid. The assignment of the spectra was achieved by the concerted use of 2D correlation spectroscopy.Dedicated to Prof. Dr. Dr. Dres. h. c. Herbert Oelschläger, Frankfurt/Main, on the occasion of his 70th birthday     

Trinuclear copper(II) complexes of some aza macrocycles

The syntheses of copper(II) complexes with neutral macrocyclic ligands 1,4,7,10,12,- 15,17,20,23,26,27,30-dodecaazadispiro[10·4·10·4]triacontane (DDST), 2,5,7,10,13,15,18,21,-23,26,29,32-dodecaazatricyclo[20·10·0·0^6,17]dotriacontane (DOCD) and 2,5,7,10,13,16,18,-21,23,26,29,32-dodecaaza-1,6,17,22-tetrachlorotricyclo[20·10·0·0^6,17]dotriacontane (DTTD) derived from triethylenetetramine, 1,2-diaminoethane and chlorocarbons (carbon tetrachloride, 1,l,2,2-tetrachloroethane and hexachloroethane, respectively) have been studied. Complexes [Cu₃(DDST)]Cl₆, [Cu₃(DOCD)]Cl₆ and [Cu₃(DTTD)]Cl₆?·?H₂O and the copper ion-free ligand hydrochlorides DDST?·?12HCl and DOCD?·?12HCl are supported by elemental analyses, conductivity measurements and spectroscopic studies. Potentiometric equilibrium studies on DDST and DOCD hydrochlorides and their copper complexes also support the structures.     

Quinazolines. VIII. Synthesis of 1,3-diaminobenzo[f]quinazolines

Twenty-one 1,3-diaminobenzo[f]quinazolines ( 2 , R = H, alkyl, halogen, methoxy) were synthesized as planar tricyclic analogs of the antimalarial agent pyrimethamine ( 1 ). The synthetic methods included i) condensation of 1-cyano-2-naphthylamines with cyanamide in the presence of pyridine hydrochloride, ii) cyclization of N¹,N⁵-bis(2-naphthyl)biguanide hydrochlorides in diphenyl ether at 250°, iii) reaction of 2-naphthylamine hydrochlorides with excess sodium dicyanamide in boiling 1-octanol, and iv) selenium dioxide dehydrogenation of 1,3-diamino-5,6-dihydrobenzo[f]quinazolines. A number of new 2-naphthols and 2-naphthylamines were synthesized as intermediates. Substituent effects on the ultraviolet absorption spectra of 1,3-diamino-benzo[f]quinazolines were investigated and found to be additive. These compounds are of interest as inhibitors of dihydrofolate reductase and as potential antimalarial and antitumor agents.     

One‐Pot Synthesis of Pyrimidines via Cyclocondensation of β‐Bromovinyl Aldehydes with Amidine Hydrochlorides

A series of pyrimidines were prepared by cyclocondensation of β‐bromovinyl aldehydes with amidine hydrochlorides in the presence of Et₃N in excellent yields (74–95%).     

Benzomorphan related compounds. III.. Structural determination of Δ3 - and Δ4-tetrahydropyridines by nuclear magnetic resonance

Observation of the nmr spectra of several Δ³ - and Δ⁴-tetrahydropyridines hydrochlorides provides a useful method for the structural determination of this type of compound. The Δ³ - Isomers exist as one predominant epimer only whereas the Δ⁴-isomers exist as a mixture of the two possible epimers. The respective assignments are discussed in view of the criteria previously applied in the study of this type of compound.