Sur l'aptitude à l'extension du noyau pipéridique en fonction de la substitution de l'atome d'azote: réaction du diazométhane avec quelques pipéridones-4 et désamination nitreuse des aminométhyl-alcools correspondants

1971 ◽  
Vol 49 (19) ◽  
pp. 3075-3085 ◽  
Author(s):  
H. Favre ◽  
Z. Hamlet ◽  
R. Lanthier ◽  
M. Ménard
Keyword(s):  
Nitrogen Atom ◽  
Carbonyl Group ◽  
Nitrous Acid ◽  
Ring Expansion ◽  
Nucleophilic Attack ◽  
Electronic Effects ◽  
Field Effects ◽  
Benzoyl Group ◽  
La Substitution

Aptitude to ring expansion in the piperidine series, measured by the ratio of ring expanded ketone to epoxide, varies considerably according to the nitrogen atom substituent. This ratio is essentially the same in the case of the reaction of diazomethane on 4-piperidones and the nitrous acid deamination of the corresponding aminoalcohols. The values of the ratio are 0.01–0.1 for a phenylsulfonyl group, of the order 0.3–0.6 for a benzoyl group and slightly greater than 1 for a benzyl group. Electronic effects (inductive and field effects) are the cause of these differences. Parallels between the two reactions indicate that nucleophilic attack of diazomethane on the carbonyl group can lead to the ring expanded ketone and the epoxide.

Correlation of structural parameters with antituberculotic activity in a group of 2-benzamidobenzothiazoles

1991 ◽  
Vol 56 (12) ◽  
pp. 2978-2985 ◽  
Author(s):  
Karel Waisser ◽  
Jiří Kuneš ◽  
Želmíra Odlerová
Keyword(s):  
Structural Parameters ◽  
Regression Equations ◽  
Electronic Effects ◽  
Active Compounds ◽  
Qsar Analysis ◽  
Active Structures ◽  
Benzoyl Group ◽  
Electronic Effects Of Substituents

Fourteen 2-benzamidobenzothiazole derivatives substituted in the benzoyl group and 2-cinnamamidobenzothiazole have been synthesized. The prediction of active structures by the method by Topliss gives incorrect results but, as shown on the basis of the Hansch QSAR analysis, the 2-(4-dimethylaminobenzamido)benzothiazole synthesized on the basis of the QSAR procedure by Topliss behaves anomalously also in the procedure by Hansch. Regression equations of the Hansch type have been found in which the antituberculotic activity is interpreted by lipophilicity and electronic effects of substituents. When tested in vitro, the most active compounds are comparable with ethionamide.

Deboronation of New Clarithromycin-Benzo[c][1,2]oxaborole Conjugates

2019 ◽  
Vol 17 (2) ◽  
pp. 99-104
Author(s):  
Gennady B. Lapa ◽  
Elena B. Isakova ◽  
Elena B. Mirchink ◽  
Maria N. Preobrazhenskaya
Keyword(s):  
Antimicrobial Activity ◽  
Molecular Modeling ◽  
Carbonyl Group ◽  
Nucleophilic Attack ◽  
Bacterial Strains ◽  
Antimicrobial Spectrum ◽  
Intramolecular Complex ◽  
Active Fragments ◽  
Proven Method ◽  
Antibacterial Spectrum

<P>Background: The conjugates of antibiotics are new molecules that might show new antibacterial spectrum and overcome resistance of insusceptible bacterial strains. Modification of known antibiotics like Clarithromycin with active fragments is laborious and proven method to overcome resistance of such strains. Methods: The conjugates of Clarithromycin and Benzo[c][1,2]oxaboroles were synthesized using long linkers to extend antimicrobial spectrum of this antibiotic. Results and Discussion: Unexpected intramolecular deboronation of these bioconjugated was found to occur when the linker contained two or more CH2-groups. Molecular modeling was used to understand the source of instability and show a possibility of intramolecular complex of carbonyl group at C-9 in Clarithromycin core and hydroxy-borole moiety. This could facilitate nucleophilic attack of methanol used in reactions to destroy benzo[c][1,2]oxaboroles fragments and leave stable hydroxyl-aryl molecules. Conclusion: The loss of boron from benzo[c][1,2]oxoborole fragments leads to the significant decrease of antimicrobial activity of synthesized antibiotics.</P>

One-pot synthesis of N-substituted-3-hydroxy-4-pyridinone chelate complexes of aluminum, gallium, and indium

1989 ◽  
Vol 67 (11) ◽  
pp. 1708-1710 ◽  
Author(s):  
Zaihui Zhang ◽  
T. L. Thomas Hui ◽  
Chris Orvig
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Nucleophilic Attack ◽  
Electronic Effects ◽  
One Pot ◽  
Group 13 ◽  
Pyrone Ring ◽  
One Pot Synthesis ◽  
Ring Nitrogen ◽  
Ring Nitrogen Atom

A series of tris(3-hydroxy-2-methyl-4-pyridinonato)metal(III) and tris(3-hydroxy-6-hydroxymethyl-4-pyridinonato)metal(III) complexes have been prepared in water by one-pot synthesis directly from maltol and kojic acid, respectively, and the metal ion (M = Al, Ga, In) with an appropriate amine. The pyridinones have substituents at the ring nitrogen atom (CH3, C2H5). The tris(3-hydroxy-4-pyronato)metal(III) complexes are formed insitu and these undergo nucleophilic attack by the primary amine; the appropriate tris(3-hydroxy-4-pyridinonato)metal(III) complexes are obtained. This method bypasses the sequential syntheses of ligand and metal complex, and has improved the yields of the tris(ligand)metal complexes, in particular by making them much more easily accessible. The electronic effects of binding the pyrone to the metal ions and of the substituents on the pyrone ring on the reactivity are discussed. Keywords: 3-hydroxy-4 pyridinone complexes, group 13 metal ions, one-pot synthesis.

Reaction of dimethoxycarbene with strained cyclic carbonyl compounds

2000 ◽  
Vol 78 (9) ◽  
pp. 1194-1203
Author(s):  
Paul C Venneri ◽  
John Warkentin
Keyword(s):  
Carbonyl Group ◽  
Carbonyl Compounds ◽  
Ring Expansion ◽  
Carbonyl Groups

A cyclopropanone, a cyclopropenone, cyclobutanones, a cyclobutane-1,3-dione, and a cyclobutene-1,2-dione reacted with dimethoxycarbene to afford acetals of the next larger ring by formal insertion of the carbene into a C—C bond α to the carbonyl group. When either of two saturated α-ring carbons could be involved in the process, the ring expansion was selective, affording primarily the product of apparent insertion into the more substituted ring bond. With 2,3-dimethoxycyclobutene-1,2-dione, insertion occurred between the carbonyl groups and with β-propiolactone it occurred at the lactone bond. β-Propiolactam, however, reacted by insertion of the carbene into the N—H bond.Key words: β-propiolactone, cyclobutanone, cyclobutananedione, cyclopropanone, dialkoxycarbene.

Metal hydride reductions of unsymmetrical cyclic anhydrides. The importance of the antiperiplanar effect on the regioselectivity of these reactions

1982 ◽  
Vol 60 (10) ◽  
pp. 1192-1198 ◽  
Author(s):  
Margaret M. Kayser ◽  
Georges Wipff
Keyword(s):  
Carbonyl Group ◽  
Metal Hydride ◽  
Lower Energy ◽  
Succinic Anhydride ◽  
Chair Conformation ◽  
Nucleophilic Attack ◽  
Quantum Mechanical ◽  
Mechanical Study ◽  
Quantum Mechanical Study ◽  
Experimental Findings

A quantum mechanical study by the SCF abinitio method of the interaction of H− with methylsuccinic and 2,2-dimethylsuccinic anhydrides (naked and in the presence of a cation) suggests that nonperpendicular rearside attack cannot be the factor responsible for the regioselectivity of hydride transfer to the more sterically hindered carbonyl group. In this model, the nucleophilic attack at the less hindered carbonyl group is calculated to be of lower energy (with or without cation). Deformation of the planar succinic anhydride ring to the quasi-chair conformation is energetically favoured as it allows the nucleophile to attack both carbonyl functions antiperiplanar to a quasi axial C—H or C—C bond. The attack antiperiplanar to the C—CH3 bond is lower in energy than the attack antiperiplanar to the C—H bond suggesting that the reduction will occur at the sterically more hindered carbonyl group which is in agreement with the experimental findings.

scholarly journals Recent Advances in the Catalytic Synthesis of Imidazolidin-2-ones and Benzimidazolidin-2-ones

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 28 ◽  
Author(s):  
Alessandra Casnati ◽  
Elena Motti ◽  
Raffaella Mancuso ◽  
Bartolo Gabriele ◽  
Nicola Della Ca’
Keyword(s):  
Natural Products ◽  
Carbonyl Group ◽  
Ring Expansion ◽  
Catalytic Synthesis ◽  
Chiral Auxiliaries ◽  
Aziridine Ring ◽  
Urea Derivatives ◽  
Structural Motifs ◽  
Recent Advances ◽  
Direct Incorporation

2-Imidazolidinone and its analogues are omnipresent structural motifs of pharmaceuticals, natural products, chiral auxiliaries, and intermediates in organic syntheses. Over the years, continuous efforts have been addressed to the development of sustainable and more efficient protocols for the synthesis of these heterocycles. This review gives a summary of the catalytic strategies to access imidazolidin-2-ones and benzimidazolidin-2-ones that have appeared in the literature from 2010 to 2018. Particularly important contributions beyond the timespan will be mentioned. The review is organized in four main chapters that identify the most common approaches to imidazolidin-2-one derivatives: (1) the direct incorporation of the carbonyl group into 1,2-diamines, (2) the diamination of olefins, (3) the intramolecular hydroamination of linear urea derivatives and (4) aziridine ring expansion. Methods not included in this classification will be addressed in the miscellaneous section.

LYCOPODIUM ALKALOIDS: VIII. LYCOPODINE

1959 ◽  
Vol 37 (10) ◽  
pp. 1757-1763 ◽  
Author(s):  
D. B. MacLean ◽  
W. A. Harrison
Keyword(s):  
Nitrogen Atom ◽  
Carbonyl Group ◽  
Lycopodium Alkaloids

Information pertaining to the position of the carbonyl group relative to the nitrogen atom and to the size of one of the nitrogen rings in lycopodine has been obtained through a study of the reactions of α- and β-cyanobromolycopodine.

scholarly journals New Syntheses and Ring Expansion Reactions of Cyclobutenimines

2010 ◽  
Vol 63 (12) ◽  
pp. 1656 ◽  
Author(s):  
Ernst Schaumann ◽  
Gerrit Oppermann ◽  
Michael Stranberg ◽  
Harold W. Moore
Keyword(s):  
Carbonyl Group ◽  
Ring Expansion ◽  
Synthetic Route ◽  
Tertiary Alcohols ◽  
Ring Enlargement ◽  
Alkyl Derivatives

Two routes are reported for the synthesis of iminocyclobutenones having N-(het)aryl substitution: an addition/substitution sequence starting with cyclobutenediones and an aza-Wittig method. A new synthetic route to N-alkyl derivatives is also presented. This involves O-alkylation of 3-alkylamino-1,2-cyclobutenediones using Meerwein’s reagent and subsequent deprotonation under non-hydrolytic conditions. Lithium organyls were found to add to the remaining carbonyl group. The resulting tertiary alcohols undergo ring enlargement on heating in xylene to give 4-aminophenols, 4-amino-1-naphthols, or cyclopenta-annulated quinolines from 4-vinyl, 4-aryl, and 4-alkynyl derivatives, respectively.

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