Structural Features in the Seven-Membered vs. Fourteen-Membered Ring Cyclization of Hydroxyamido Ketals Derived from β-Amino Alcohols

Author(s):  
Anne-Gaëlle Valade ◽  
Denise Dugat ◽  
Georges Jeminet ◽  
Jacques Royer ◽  
Henri-Philippe Husson
1964 ◽  
Vol 42 (1) ◽  
pp. 20-24 ◽  
Author(s):  
W. A. Szarek ◽  
J. K. N. Jones

The synthesis of methyl 4-acetamido-4-deoxy-L-erythrofuranoside from D-ribose is described. The structural features that are believed to be necessary for the replacement of the ring oxygen of sugars by nitrogen are discussed.


Química Nova ◽  
2021 ◽  
Author(s):  
Sara Sousa ◽  
Róbson Teixeira ◽  
Adilson Costa ◽  
Alex Aguiar ◽  
Victor Fonseca ◽  
...  

SYNTHESIS OF NOVEL 1,2,3-TRIAZOLES INSPIRED ON THE SRPIN340 AND EVALUATION OF THEIR EFFECTS ON HUMAN GLIOBLASTOMA CELL LINE. It is herein described the synthesis of a series of thirty novel 1,2,3-triazole1,4-disubstituted compounds inspired on the known SRPKs inhibitor N-(2-(piperidin-1-yl)-5-(trifluoromethyl)phenyl)isonicotinamide (SRPIN340) and biological evaluation of them against human glioblastoma multiforme cell line U87MG. Starting with 1-fluoro2-nitro-4- (trifluoromethyl)benzene (1), the substances were prepared via a five-step synthetic route. The crucial step corresponded to the copper-catalyzed cycloaddition reaction between trifluoromethyl phenyl azides and different alkynes. In general, the compounds were obtained with good yields and they were characterized utilizing spectroscopic (IR and NMR) and spectrometric (HRMS) techniques. The evaluation of the synthesized compounds at three different treatment time (24 h, 48 h, and 72 h) and concentrations (50, 100, and 150 µmol L-1) revealed that five derivatives were capable of reducing cell viability by 50% after 72 h of treatment at the highest concentration. On the contrary, three derivatives significantly increased cell viability being this effect more pronounced after 48 h of treatment. In this regard, it stands out the compound 2-((1-(2-morpholino-5-(trifluoromethyl)phenyl)-1H-1,2,3-triazol4-yl)methyl)isoindoline-1,3-dione (7) which increased cell viability in approximately 300% after 48 h of treatment at 100 µmol L-1. The substances that increased cell viaiblity present as common structural features the presence of a saturated nitrogen-containing six-membered ring and carbonylated fragments.


2004 ◽  
Vol 6 (16) ◽  
pp. 2785-2788 ◽  
Author(s):  
Ken-ichi Fujita ◽  
Yoshinori Takahashi ◽  
Maki Owaki ◽  
Kazunari Yamamoto ◽  
Ryohei Yamaguchi
Keyword(s):  

2019 ◽  
Author(s):  
Zheng Huang ◽  
Jean-Philip Lumb

Noncanonical oxygenases are a family of Fe-containing enzymes that catalyze oxidative radical cyclizations. Despite creating key structural features that often define a natural product’s complexity, the mechanisms of these oxidations remain poorly understood and difficult to mimic. In this work, we show that noncanonical cyclizations from lignan biosynthesis can be recreated when presumed biosynthetic radicals are generated using photocatalysis. These conditions afford the ensuing electron rich radicals sufficient time to undergo challenging 5- or 11-membered ring formation that create the defining structural features of the highly oxidized lignans taiwankadsurins A, B and kadsuphilin N. By showing that these cyclizations can occur without enzymatic assistance, we provide a more general strategy for mimicking noncanonical transformations that should broaden their use in organic synthesis.


2006 ◽  
Vol 62 (6) ◽  
pp. 1112-1120 ◽  
Author(s):  
Valerio Bertolasi ◽  
Loretta Pretto ◽  
Valeria Ferretti ◽  
Paola Gilli ◽  
Gastone Gilli

The crystal structures of five β-enaminones are reported: (2Z)-3-(benzylamino)-1,3-diphenyl-prop-2-en-1-one, (2Z)-3-(benzylamino)-3-(2-hydroxyphenyl)-1-phenyl-prop-2-en-1-one, (2Z)-3-(benzylamino)-3-(4-methoxyphenyl)-1-(3-nitrophenyl)-prop-2-en-1-one, 2-{1-[(4-methoxyphenyl)amino]ethylidene}cyclohexene-1,3-dione and 2-{1-[(3-methoxyphenyl)amino]ethylidene}cyclohexene-1,3-dione. The structures were analysed and compared with those of similar compounds in order to establish which factors determine the range (2.53–2.72 Å) of N...O hydrogen-bond distances in intramolecularly hydrogen-bonded β-enaminones. It has been shown that, beyond electronic resonance-assisted hydrogen-bond effects modulated by substituents, the necessary requirements to produce very short N—H...O hydrogen bonding are steric intramolecular repulsions, including the embedding of an enaminonic C—C or C—N bond in an aliphatic six-membered ring. By considering the structural features it is possible to expect the strength of N—H...O hydrogen bonds adopted by specific β-enaminones.


1959 ◽  
Vol 37 (12) ◽  
pp. 2007-2022 ◽  
Author(s):  
R. N. Jones ◽  
C. L. Angell ◽  
T. Ito ◽  
R. J. D. Smith

Certain types of unsaturated lactones exhibit two bands in the region of the spectrum associated with the C=O stretching vibrational mode. This is observed both in the infrared and Raman spectra.The infrared spectra of 23 simple saturated and unsaturated lactones have been examined in an attempt to determine the structural features with which this carbonyl band splitting is associated. It appears to be common to most unsaturated five- and six-membered ring lactones in which the double bond is conjugated with the carbonyl group, though one well-established exception has been observed. The relative intensities of the two bands are extremely sensitive to changes in the polarity of the solvent; they also vary reversibly with temperature but are independent of concentration.The splitting of the C=O stretching band is attributed to an intramolecular vibrational effect similar to that which occurs in cyclopentanone and in certain Δ2-cyclopentenone derivatives. Its possible dependence on Fermi resonance with the overtone of a lower lying fundamental vibration is discussed.Similar effects occur in other types of carbonyl compounds, such as benzoyl chloride and cyclic five-membered ring anhydrides, and care is needed to distinguish carbonyl band splitting of this kind from that associated with equilibria between conformational isomers.


ChemInform ◽  
2004 ◽  
Vol 35 (48) ◽  
Author(s):  
Ken-ichi Fujita ◽  
Yoshinori Takahashi ◽  
Maki Owaki ◽  
Kazunari Yamamoto ◽  
Ryohei Yamaguchi
Keyword(s):  

2019 ◽  
Author(s):  
Zheng Huang ◽  
Jean-Philip Lumb

Noncanonical oxygenases are a family of Fe-containing enzymes that catalyze oxidative radical cyclizations. Despite creating key structural features that often define a natural product’s complexity, the mechanisms of these oxidations remain poorly understood and difficult to mimic. In this work, we show that noncanonical cyclizations from lignan biosynthesis can be recreated when presumed biosynthetic radicals are generated using photocatalysis. These conditions afford the ensuing electron rich radicals sufficient time to undergo challenging 5- or 11-membered ring formation that create the defining structural features of the highly oxidized lignans taiwankadsurins A, B and kadsuphilin N. By showing that these cyclizations can occur without enzymatic assistance, we provide a more general strategy for mimicking noncanonical transformations that should broaden their use in organic synthesis.


2021 ◽  
Author(s):  
Jared Shaw ◽  
Anna Lo ◽  
David Gutierrez ◽  
Garrett Toth-Williams ◽  
James Fettinger

Lewis-acid mediated allylations of β-alkoxy N-tosyl imines lead to 3-alkoxy homoallylic N-tosyl amines with anti diastereoselectivity. Diastereoselectivity and yields of reactions are comparable between two methods of Hosomi-Sakurai allylations. Observed selectivity trends and computational evidence suggest that 1,3 asymmetric induction occurs through the formation of a six- membered ring chelate which adopts a half-chair-like conformation. The product ratios of allylations to β-alkoxy N-tosyl imines are dependent on conformation preferences of the chelate and stereoelectronic interactions in the transition-state structures. Debenzylation and detosylation of these allylation products result in anti 1,3-amino alcohols, a privileged motif in synthetic and natural bioactive compounds.


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