Conformational analysis about the N-N bond by N.M.R. spectroscopy: N'-sulphonyl derivatives of N-Aminobicyclo[2,2,1]hept-5-ene-endo-2,3-dicarboximide

1974 ◽  
Vol 27 (6) ◽  
pp. 1227 ◽  
Author(s):  
SM Verma ◽  
Rao C Koteswara
Keyword(s):  
Conformational Analysis ◽  
Conformational Changes ◽  
Ground States ◽  
Spectral Changes ◽  
Rotational Barriers ◽  
Tosyl Group ◽  
Derivatives Of ◽  
Acyl Derivatives

A series of N'-sulphonyl and N'-acyl derivatives of N-aminobicyclo[2,2,1]hept-5-ene-endo-2,3-dicarboximide have been synthesized and their conformations have been investigated by N.M.R.spectroscopy. The effect of the sulphonyl group at the exocyclic nitrogen on the conformational process about the N-N bond has been studied. Existence of non-planar ground states about the N-N bond in the N',N?-disulphonyl and N'-sulphonyl-N'-acyl derivatives has been demonstrated.Temperature-dependent spectral changes have been related to the conformational changes about the N-N bond. It has been shown that the N'-tosyl substituent assumes a preferred conformation about the N-SO2 bond; the aryl part of the tosyl group lies exo to the cage-moiety. The N'-tosyl-N'-aroyl derivatives also show a preferred conformation about the N'-aroyl bond, the aryl part of the aroyl group lying endo to the cage-moiety. The N'-acetyl-N'-aroyl derivatives have been shown toexhibit low rotational barriers about the N'-aroyl bond.

Conformational analysis about the N-N bond by P.M.R. spectroscopy: N'-derivatives of N-amino-1,2,3,4-tetrahydro-9-oxo-1,4-ethanonaphthalene-endo-2,3-dicarboximide

1973 ◽  
Vol 26 (9) ◽  
pp. 1963 ◽  
Author(s):  
SM Verma ◽  
O Subba Rao
Keyword(s):  
Maleic Anhydride ◽  
Conformational Analysis ◽  
Conformational Changes ◽  
Major Product ◽  
Diels Alder ◽  
Conformational Study ◽  
Temperature Dependent ◽  
Spectral Changes ◽  
Derivatives Of

A series of N?-derivatives of N-amino-1,2,3,4-tetrahydro-9-oxo-1,4- ethanonaphthalene-endo-2,3-dicarboximide have been prepared and their p.m.r. spectra studied. The non-planar ?cage-moiety? structure has been used in the conformational study. Temperature dependent spectral changes have been related to conformational changes about the N-N bond. ��� The endo configuration of the major product obtained in Diels-Alder addition of maleic anhydride on β-naphthol has been strongly evidenced.

Catalyst-Control over Sixfold Stereogenicity

2020 ◽  
Author(s):  
Xingxing Wu ◽  
Reto M. Witzig ◽  
Rodolphe Beaud ◽  
Christian Fischer ◽  
Daniel Häussinger ◽  
...  
Keyword(s):  
Conformational Analysis ◽  
Higher Order ◽  
Binary Codes ◽  
Rotational Barriers ◽  
Molecular Architectures

Governing higher-order stereogenicity is a long-standing goal in stereoselective catalysis, because it allows to achieve selectivity for more than a twofold number of stereoisomers per stereogenic unit. Current methods warrant control over the power of two stereoisomers and the configurations are routinely assigned using the descriptors ( R ) and ( S ), or related binary codes. In contrast, conformational analysis ranges beyond this dualistic treatment of stereoisomerism, which constitutes an unmet challenge for catalyst stereocontrolled processes. Herein, we now report that sixfold stereogenicity can be governed by stereoselective catalysis. By controlling a configurationally stable stereogenic axis with six large rotational barriers, a catalytic [2+2+2]-cyclotrimerization selectively governs the formation of one out of six stereoisomers with up to 0:0:2:98:0:0 stereocontrol. The underpinnings of conformational analysis and stereoselective catalysis are thereby conceptually reunited. Novel molecular architectures featuring distinct chemical topologies and unexplored chemical designs are anticipated from catalystcontrol over higher-order stereogenicities

scholarly journals Synthesis, Antiproliferative Activity and Radical Scavenging Ability of 5-O-Acyl Derivatives of Quercetin

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1608
Author(s):  
Stephen Lo ◽  
Euphemia Leung ◽  
Bruno Fedrizzi ◽  
David Barker
Keyword(s):  
Antiproliferative Activity ◽  
Biological Activities ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Breast Cancer Cell Lines ◽  
Scavenging Activity ◽  
Plant Materials ◽  
Wide Range ◽  
Derivatives Of ◽  
Acyl Derivatives

Quercetin is a flavonoid that is found in many plant materials, including commonly eaten fruits and vegetables. The compound is well known for its wide range of biological activities. In this study, 5-O-acyl derivatives of quercetin were synthesised and assessed for their antiproliferative activity against the HCT116 colon cancer and MDA-MB-231 breast cancer cell lines; and their radical scavenging activity against the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical species. Four derivatives were found to have improved the antiproliferative activity compared to quercetin whilst retaining radical scavenging activity.

Sign in / Sign up

Export Citation Format

Share Document