The role of the ester group in determining the regiochemistry of selected β-amino and β-ammonio radical cyclisations: generation of 1-azabicyclo[3.2.1]octyl- and -[2.2.2]octyl systems

2001 ◽  
pp. 445-452 ◽  
Author(s):  
Ernest W. Della ◽  
Paul A. Smith
Keyword(s):  
Ester Group ◽  
Radical Cyclisations

The asymmetric Michael-type alkylation of chiral β-enamino esters: critical role of a benzyl ester group in the racemization of adducts

2005 ◽  
Vol 16 (23) ◽  
pp. 3853-3857 ◽  
Author(s):  
Mathieu Pizzonero ◽  
Frédéric Hendra ◽  
Sandrine Delarue-Cochin ◽  
Marie-Elise Tran Huu-Dau ◽  
Françoise Dumas ◽  
...  
Keyword(s):  
Critical Role ◽  
Ester Group ◽  
Benzyl Ester

scholarly journals On the Thermodynamic Control of Ring Opening of 4-Substituted 1,3,3-Tris-Carbethoxycyclobutene and the Role of the C-3 Substituent in Masking the Kinetic Torquoselectivity. An alternate reaction pathway

2021 ◽  
Author(s):  
Veejendra Yadav ◽  
Dasari L V K Prasad ◽  
Arpita Yadav ◽  
Maddali L N Rao
Keyword(s):  
Lewis Acid ◽  
Ring Opening ◽  
Reaction Pathway ◽  
Chloride Ion ◽  
Ester Group ◽  
Heterolytic Cleavage ◽  
Acid Catalyzed ◽  
Halogen Acid

<p>The predominant transformations of 4-methyl- and 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutenes to s-<i>trans</i>,<i>trans</i>-1,1,3-<i>tris</i>-carbethoxy-4-methyl- and s-<i>trans</i>,<i>trans</i>-1,1,3-<i>tris</i>-carbethoxy-4-phenyl-1,3-butadienes, respectively, are discussed to proceed through pathways entailing heterolytic cleavage of the s<sub>C3C4</sub> bond rather than the usual conrotatory ring opening following the rules of torquoselectivity. The adventitious or in situ generated halogen acid from CDCl<sub>3</sub> catalyzes the reaction by protonation of the geminal ester group to weaken s<sub>C3C4</sub> bond and allow its S<sub>N</sub>2 cleavage by chloride ion. This is followed by cisoid<b>→</b>transoid isomerization and loss of the elements of halogen acid to form the products. In the Lewis acid-catalyzed reaction of 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutene in CH<sub>2</sub>Cl<sub>2</sub>, coordination of Lewis acid with the geminal ester group is followed by heterolytic cleavage of the s<sub>C3C4</sub> bond. The resultant species subsequently undergoes cisoid<b>→</b>transoid isomerization before losing the Lewis acid to form the products.<br></p>

Triazene metabolism. II Transportability and enzyme inhibitory characteristics of metabolites of antitumor dimethyltriazenes

1981 ◽  
Vol 59 (12) ◽  
pp. 1239-1244 ◽  
Author(s):  
James R. P. Godin ◽  
Gerard Llanos ◽  
Keith Vaughan ◽  
Kenneth W. Renton
Keyword(s):  
Enzyme Activity ◽  
Enzyme Inhibition ◽  
Absorption Maximum ◽  
Ester Group ◽  
Significant Inhibition ◽  
Inhibitory Effects ◽  
Reversible Inhibition ◽  
Liver Esterase ◽  
Rate Of Hydrolysis

A series of dimethyltriazenes (Ar∙N=N∙NMe2), monomethyltriazenes (Ar∙N=N∙NH∙Me), and triazene carbinolamines (Ar∙N=N∙NMe∙CH2OH) have been studied for their inhibitory effects on the enzyme, hog liver esterase (EC 3.1.1.1). p-Nitrophenyl acetate was used as the model substrate and the rate of hydrolysis was followed spectrophotometrically at 400 nm, the absorption maximum of the p-nitrophenylate ion. Only triazenes with an ester group in the aryl moiety exhibited significant inhibition. Preincubation of the enzyme with the monomethyltriazene (MeO2C∙C6H4∙N=N∙NHMe) or the methyloltriazene (MeO2C∙C6H4∙N=N∙NMe∙CH2OH) gave enhanced inhibition, which was not observed when the dimethyltriazene (MeO2C∙C6H4∙N=N∙NMe2) was preincubated with the enzyme. Inhibition of enzyme activity by the monomethyltriazene was shown to be essentially irreversible, whereas the model substrates, methyl benzoate and methyl p-aminobenzoate, gave reversible inhibition in the same assay. The inhibition by the N-methyloltriazene was only partially reversible. The results are discussed with relevance to the role of the monomethyltriazenes and N-methyloltriazenes as possible transportable metabolites of the antitumour dimethyltriazenes.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

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