1H and 13C NMR study of 8-hydroxyquinoline and some of its 5-substituted analogues

¹H and ¹³C NMR spectra of 8-hydroxyquinoline (oxine) and its 5-Me, 5-F, 5-Cl, 5-Br and 5-NO₂ derivatives have been studied in DMSO-d₆ solution. The ¹H and ¹³C chemical shifts and proton–proton, proton–fluorine, carbon–proton and carbon–fluorine coupling constants have been determined. The ¹H and ¹³C chemical shifts have been correlated with the charge densities on the hydrogen and carbon atoms calculated by the CNDO/2 method. The correlation of the ¹H and ¹³C chemical shifts with the total charge densities on the carbon atoms is approximately linear (r_H² = 0.85, r_C² = 0.84). The proton in peri position to the nitro group in 5-NO₂-oxine is an exception.     

Nucleophilic addition to substituted 1H-4,5-dihydroimidazolium salts

1H-4,5-Dihydroimidazolium salts 1 react readily with nucleophilic reagents originating cyclic products which may be stable or become transformed into acyclic compounds maintaining the structural ethylenediamine unit. With methylmagnesium iodide compound 1e affords the expected imidazolidine, but in the case of substituted 1-aryl-3-methyl-2-phenyl salts 1b-d the N-aryl-N′-methylethylenediamines 3b-d and acetophenone ( 4 ) were isolated, the process representing the transfer of the C-2 unit to a nucleophilic carbon. With alkaline cyanides salts 1 react efficiently affording α,α-diaminonitriles 5 . In these compounds the cyano group may be readily substituted by nucleophiles (hydroxyl anion, species with nucleophilic carbon and reagents that act by hydride ion transfer), in a way similar to the salts but with better yields.     

Stereochemical effects in the nitrosation of some α,β-unsaturated ketoximes. Formation of 1-hydroxypyrazole 2-oxides and 4-oximino-4,5-dihydroisoxazoles

Several α,β-unsaturated ketoximes R¹CH=CHC(=NOH)R² were nitrosated using butyl nitrite in aqueous ethanol in the presence of copper(II) sulfate and pyridine. The product distribution varied depending on whether the oxime hydroxyl group was syn or anti with respect to the carbon?carbon double bond. The anti-oximes gave the copper complexes of 1-hydroxypyrazole 2-oxides in high yields. The isomeric syn-oximes gave lower yields of the pyrazole complexes along with 4-oximino-4,5-dihydroisoxazole derivatives. For the syn-oximes where R¹ is phenyl and R² is either methyl or ethyl, conversion of the oximes to the parent ketones was also observed. The results may be explained by processes involving N-nitrosonitrone intermediates.     

Some reactions of 4-aryl-1 (2H)-phthalazinones

The behaviors of 4-aryl-1 (2H)-phthalazinones (1a–c) toward carbon nucleophiles (Grignard reagents) and secondary amine under Mannich conditions as well as the nucleophilic substitution reaction on chlorophthalazine derivatives have been studied.     

Palladium-Catalyzed Cyclocarbonylation of 2-Halobenzaldehyde and Hydrazines: A Facile Synthesis of 2-Aminoisoindolin-1-ones

An efficient procedure for the synthesis of 2‐aminoisoindolin‐1‐ones via a palladium‐catalyzed three‐component reaction of 2‐halobenzaldehydes, hydrazines and carbon monoxide is reported. This cyclocarbonylation process can be performed smoothly under 1 atmospheric pressure of carbon monoxide to afford 2‐aminoisoindolin‐1‐ones in moderate to excellent yields.     

Vicinal Dibromo and Hydroxy(methoxy) Bromo Derivatives of (1R,4R)-7,7-Dimethyl-1-vinylnorbornan-2-one. Regio- and Stereoselectivity Aspects

Reactions of (1R,4R)-7,7-dimethyl-1-vinylnorbornan-2-one with bromine in carbon tetrachloride and with N-bromosuccinimide in methanol gave the corresponding C^{1 '}-epimeric dibromo and methoxy bromo derivatives. Their structure was determined on the basis of spectral data.     

A FACILE SYNTHESIS OF DIETHYL 1- ISOTHIOCYANO)ALKYLPHOSPHONATES[1]

Abstract

Novel, diethyl 1-(isothiocyano)alkylphosphonates 3 have been efficiently synthesized via a one-pot reaction of diethyl 1-azidoalkylphosphonates 1 with triphenylphosphine, followed by in situ transformation of thus formed phosphazenes 2 with carbon disulfide. Application of the title compounds in the synthesis of diethyl (N-phenylthioureido)- and (benzothiazol-2-ylamino)methylphosphonates was also described.     

Asymmetric polymerization using C1 resources

Two examples of asymmetric alternating copolymerization, (1) the alternating copolymerization of α‐olefins (monosubstituted ethenes) with carbon monoxide and (2) the alternating copolymerization of meso‐epoxide with carbon dioxide, are described, and the meaning of chirality in polymer synthesis is emphasized. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 215–221, 2004     

Die Protonierung von 1-Formyl- und 1-Acetyl-azulenen

NMR. data show that protonation of 1-formyl-azulene yields essentially a one-to-one mixture of conjugate acids in which the hydroxyl group assumes the syn-planar or anti-planar configuration relative to the tropylium nucleus. The presence of a minute amount of protonation in position 3 is demonstrated by the rapid hydrogendeuterium exchange in this position. Steric interference in 1-formyl-azulenes with a methyl group in the peri position 8 favours the anti-planar configuration. As shown by one example, the conjugate acids of 1-acetyl-azulenes without substituents in positions 2 or 8 assume the anti-planar configuration. In 1-acetyl-azulenes carrying a methyl group in position 8, addition of a proton to the carbon centre 1 is the preferred route of protonation, as a consequence of the accompanying strain release.     

Lithiation of 1-benzylimidazole. A hypothesis on the regioselectivity of the electrophilic attacks on the lithiated species

Sequential lithiations of 1-benzylimidazole, 1 , and of 1-benzyl-1,2,4-triazole, 2 , followed by treatment with electrophiles others than alkyl halides result in reactions at C-2. However, benzyl halides and, to a certain extent, iodomethane react at the N-benzyl carbon atom. An explanatory hypothesis based on steric ortho effects is advanced.     

Selenium-Containing Heterocycles. Synthesis and Reactions of 2-Amino-4,5,6,7-tetrahydro-1-benzoselenophene-3-carbonitrile with Anticipated Biological Activity

Reaction of 2-amino-4,5,6,7-tetrahydro-1-benzoselenophene-3-carbonitrile with ethylenediamine in the presence of a catalytic amount of carbon disulfide afforded 2-amino-3-(4,5-dihydro-1H-imidazol-2-yl)-4,5,6,7-tetrahydro-1-benzoselenophene. Cyclocondensation of the latter with triethyl orthoformate, benzaldehyde, and carbon disulfide gave tetracyclic imidazobenzoselenophenopyrimidine derivatives. Treatment of 2,3,5,6,8,9,10,11-octahydroimidazo[2,1-c][1]benzoselenopheno[3,2-e]pyrimidine-5-thione with hydrazine hydrate led to the corresponding 5-hydrazino derivative whose reactions with triethyl orthoformate and sodium nitrite were accompanied by closure of 1,2,4-triazole and tetrazole rings, respectively. Fused benzoseleno-phenopyrimidine systems were also obtained by reaction of 2-amino-4,5,6,7-tetrahydrobenzo-1-selenophene-3-carbonitrile with formamide, carbon disulfide, and phenyl isothiocyanate. Some newly synthesized compounds were tested for antimicrobial and antifungal activity.__________From Zhurnal Organicheskoi Khimii, Vol. 41, No. 3, 2005, pp. 406–410.Original English Text Copyright © 2005 by Abdel-Hafez.The original article was submitted in English.This study was presented at the 7th IUPAC International Conference on Heteroatom Chemistry (ICHAC-7), Shanghai, August 20–25, 2004.     

Novel heterocycles. 10. Reactions of 1,3,2-benzodiazaphosphorin-4(1H)-one 2-oxides

Reactions of 1,3-disubstituted-2,3-dihydro-1,3,2-benzodiazaphosphorin-4 (1 H)-one 2-oxides ( 1 ) with various electrophiles were investigated. The treatment of 1 with aldehydes in the absence of a basic catalyst directlyafforded alcohols 7a-h in good yield. The product from the reaction of 1 with chloral, on treatment with sodium hydride, resulted in the formation of a dichloroepoxide ( 8 ). When 1 was allowed to react with isocyanates or isothiocyanates in the presence of triethylamine, amides 10a-e and thioamide 11 were produced in good yield. Compounds 1a and 1b were readily halogenated on their phosphorus atom by treatment with either carbon tetrachloride or carbon tetrabromide and triethylamine. The P-chloro compound 12a reacted with ethanol to furnish the P-ethoxy derivative 13 and, in an attempt to react 12a with bis (2-chloroethyl) amine, anhydride 14 was formed in high yield. Spectral data for the majority of the products are also discussed.     

Amine-carbon disulfide promoted synthesis of novel benzo[e][1,3]thiazepin-5(1H)-one derivatives

In this paper, a simple method is introduced for the synthesis of novel 4-substituted-3-thioxo-3,4-dihydrobenzo[e][1,3]thiazepin-5(1H)-one derivatives. The synthesis is based on a two-step reaction of 2-methylbenzoic acid, an amine, and carbon disulfide. In the first step, 2-methylbenzoic acid reacts with sulfuric acid in ethanol, followed by the reaction with N-bromosuccinimide to produce ethyl 2-(bromomethyl)benzoate. Amine and carbon disulfide react in a separate flask in basic medium to give carbamodithioate salt. Carbamodithioate and ethyl 2-(bromomethyl)benzoate react together in dimethylformamide to produce the desired 4-substituted-3-thioxo-3,4-dihydrobenzo[e][1,3]thiazepin-5(1H)-one derivatives. The method is simple and fast and is applicable to a wide variety of substrates and gives the desired products in high isolated yields.     

An Efficient Synthesis of Novel 2‐(5‐indolyl)‐1H‐benzimidazole Derivatives and Evaluation of Their Antimicrobial Activities

In this paper, we report the synthesis of novel 2‐(5‐indolyl)‐1H‐benzimidazole derivatives. The methodology involves the Sonogashira reaction of 4‐(1H‐benzimidazol‐2‐yl)‐2‐bromo‐N,N‐dimethylaniline ( 3 ) with variety of terminal alkynes to get corresponding novel 4‐(1H‐benzimidazol‐2‐yl)‐2‐alkynyl‐N,N‐dimethylaniline derivatives ( 4 ). These compounds on iodocyclization afforded novel iodoindolylbenzimidazole derivatives ( 5 ). The resulting compounds were functionalized further via palladium‐mediated carbon–carbon bond formation for generating novel structurally diversified heterocyclic compounds. All these newly synthesized compounds were evaluated for antimicrobial activity.     

Carbon-13 assignments in 1- and 2-naphthyl compounds: Extensive benefits of deuterium substitution

The natural abundance, proton-decoupled carbon-13 spectra of 1-methylnaphthalene, 1-fluoronaphthalene, l-naphthonitrile and their 4-deutero analogues, as well as 2-naphthol and its 6-deutero analogue, have been recorded. Careful comparisons of the spectra of the deuterated and undeuterated compounds allow assignment, not only of the deuterated carbon, but also of the two ortho carbons (based on an upfield ‘two-bond’ deuterium isotope effect), as well as the two meta carbons (based on a significant J(CCCD) of ～1 Hz) which causes substantial broadening). In the 1-naphthyl compounds, significant coupling between the deuterium (at C₄) and C₅ allows assignment of this latter carbon. Thus, the consequences of the introduction of one deuterium atom, together with results from off-resonance noise decoupling, permits assignment of most of the spectra. Tentative, but very likely assignments of the few remaining signals, can be made on the bases of chemical shifts and compressional effects. This approach could allow indirect assignment of an aryl carbon to which direct attachment of deuterium is difficult, due to directive effects of an existing substituent.     

Inversion of 1JCC correlations in 1,n‐ADEQUATE spectra

ADEQUATE experiments provide an alternative to the more commonly employed GHMBC experiment for the establishment of long‐range heteronuclear connectivities. The 1,1‐ADEQUATE experiment allows the unequivocal identification of both protonated and non‐protonated carbon resonances adjacent to a protonated carbon. The 1,n‐ADEQUATE experiment establishes correlations via an initial ¹J_CH heteronuclear transfer followed by an ⁿJ_CC out‐and‐back transfer, most typically, via three carbon–carbon bonds. Hence, the 1,n‐ADEQUATE experiment allows the equivalent of ⁴J_CH heteronuclear correlations to be probed when they are not observed in a GHMBC spectrum. Aside from the lower sensitivity of the 1,n‐ADEQUATE experiment relative to GHMBC experiments, the interpretation of the former is also complicated by the ‘leakage’ of ¹J_CC correlations into the spectrum that must be identified. A method for the inversion of ¹J_CC correlations to facilitate the interpretation of 1,n‐ADEQUATE spectra is presented that allows a single experiment to be performed to access ¹J_CC and ⁿJ_CC correlation information. Copyright © 2012 John Wiley & Sons, Ltd.     

Steric interactions in 2-substituted imidazoles. The molecular structure of 1-methyl-2-phenylimidazole and 1-methyl-4-phenylimidazole

The crystal and molecular structures are reported for two isomeric imidazoles: 1-methyl-2-phenylimida-zole ( 1 ) and 1-methyl-4-phenylimidazole ( 2 ). In molecule 2 the phenyl ring is rotated by 7.3° from the het-erocyclic plane due to steric interactions. The steric congestion is much more severe in 1 , with the adjacent methyl and phenyl substituents mininizing nonbonded interactions via a 32.3° rotation of the phenyl ring and a 0.159 Å displacement of the methyl carbon from the heterocyclic plane.     

Simultaneous determination of heats,equilibrium and kinetics of adsorption: 1- Ethoxy-2-propanol vapours

The heat, equilibrium, and kinetics of adsorption of 1-ethoxy-2-propanol vapours on granulated activated carbon were determined simultaneously by a reaction calorimeter SETARAM C80 D at T=298.15 K at various relative vapour pressures (0.1< p/p_s<0.8). The adsorption isotherm was correlated by the Freundlich equation. It was observed that the enthalpies of adsorption decrease slightly with increasing of the relative vapour pressure of the adsorptive. The rate of adsorption were calculated from analysis of the heat flux signals and it was found that the mass-transfer coefficient for 1-ethoxy-2-propanol vapours in granulated activated carbon increased with increasing relative vapour pressure of the adsorptive.This revised version was published online in November 2005 with corrections to the Cover Date.     

High resolution mass spectrometry—V: Cyclic esters of aliphatic α-hydroxy acids

The main fragmentation sequences of glycollide and its homologues are initiated by fission of a CO? O bond, leading to the formation of fragment ions of low, m/e, such as [R¹CO]⁺ and [CR¹R²CCO]⁺. When a hydrogen atom is present on a ring carbon atom, 1,3 hydrogen migration occurs to produce [CHR²OH]⁺. In case where a ring carbon atom carries an alkylchain ? C₂H₅, a McLafferty rearrangement occurs with the adjacent carbonyl group. When both ring carbon atoms are dimethyl substituted, a 1,4 hydrogen migration must be invoked to account for the observed fragmentation sequence.     

Umwandlung der diastereomeren 12- und 6-gliedrigen 1-Acetyl-2-methyl-1-cycloalkanole in 1-Äthinyl-2-methyl-1-cycloalkene

Conversion of the Diastereoisomeric 12-and 6-membered 1-Acetyl-2-methyl-1-cycloalkanols to 1-Ethynyl-2-methyl-1-cycloalkenes This paper is concerned primarily with a derivation of the E-configuration of 1-ethynyl-2-methyl-1-cyclododecene ( 10 ), which plays a role in mechanistic considerations on a method for ring expansion by 3 carbon atoms described in apreceding paper [1]. The derivation is based on an argument using the results of the dehydration of trans-1-acetyl-1-2-methyl-1-cyclododecanol ( 4 ) to 10 with phosphorus oxychloride and pyridine. That this dehydration is stereospecific can be concluded from its regiospecificity since the cis-hydroxyketone 3 dehydrates mainly to 1-ethynyl-12-methyl-1-cyclododecene (mixture of stereoisomers 11 and 12 ). An x-ray analysis shows the indicated configurations of the two hydroxyketones 3 and 4 . The direction (anti) of the stereospecificity of the double bond introduction during the 4 → 10 conversion is deduced from the similarity of the behaviour of the two stereoisomeric 1-acetyl-2-methyl-1-cyclohexanols 8 and 9 under the same conditions and from mechanistic considerations, which make it likeley that the anti-elimination behaviour observed in the 6-membered system has not changed over to a syn-elimination behaviour in the 12-membered system. The configurations of the two 6-membered hydroxyketones 8 and 9 correspond to those of the precursor1-ethynyl-2-methyl-1-cyclohexanols 6 and 7 , which were clarified with the help of ¹³C-NMR.-spectral coupling observations. It is of interest that the hydroxyketones 3, 4, 8 and 9 react with phosphorus oxychloride and pyridine so as to introduce both a double and a triple bond. It is probable that the double bond is introduced first, inasmuch as the triple bond is not introduced in the absence of activation of the hydroxyl group, as for instance in acetylcyclohexane. This can be used as an argument that the conversion of the acetyl to an ethynyl group in 3, 4, 8 and 9 does not affect the stereospecificity of the dehydration which introduces the ring double bond. 1-Acetyl-2-methyl-1-cyclododecene ( 24 ), a previously isolated compound with pleasant odor, was synthesized by hydration of 10 . This furnishes an argument for the E-configuration of 24 .