scholarly journals Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations

2010 ◽  
Vol 6 ◽  
pp. 1229-1245 ◽  
Author(s):  
Jakub Saadi ◽  
Irene Brüdgam ◽  
Hans-Ulrich Reissig
Keyword(s):  
Systematic Study ◽  
Steric Hindrance ◽  
Structural Features ◽  
Samarium Diiodide ◽  
Cyclization Reactions ◽  
Substitution Pattern ◽  
High Importance

A series of γ-oxo esters suitably substituted with various styrene subunits was subjected to samarium diiodide-induced 8-endo-trig cyclizations. Efficacy, regioselectivity and stereoselectivity of these reactions via samarium ketyls strongly depend on the substitution pattern of the attacked alkene moiety. The stereoselectivity of the protonation of the intermediate samariumorganyl is also influenced by the structural features of the substrates. This systematic study reveals that steric and electronic factors exhibited by the alkene and ketone subunits are of high importance for the outcome of these cyclization reactions leading to highly substituted benzannulated cyclooctanol derivatives. In exceptional cases, 7-exo-trig cyclizations to cycloheptanol derivatives have been observed. In examples with high steric hindrance the ketyl–aryl coupling can be a competing process.

scholarly journals [1,5]-Hydride Shift-Cyclization versus C(sp2)-H Functionalization in the Knoevenagel-Cyclization Domino Reactions of 1,4- and 1,5-Benzoxazepines

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1265 ◽  
Author(s):  
Dóra Szalóki Vargáné ◽  
László Tóth ◽  
Balázs Buglyó ◽  
Attila Kiss-Szikszai ◽  
Attila Mándi ◽  
...  
Keyword(s):  
Density Functional ◽  
Time Dependent ◽  
Chiral Hplc ◽  
Cyclization Reactions ◽  
Substitution Pattern ◽  
Functional Theory ◽  
Hydride Shift ◽  
Ic50 Value ◽  
Active Methylene ◽  
Methylene Group

Domino cyclization reactions of N-aryl-1,4- and 1,5-benzoxazepine derivatives involving [1,5]-hydride shift or C(sp2)-H functionalization were investigated. Neuroprotective and acetylcholinesterase activities of the products were studied. Domino Knoevenagel-[1,5]-hydride shift-cyclization reaction of N-aryl-1,4-benzoxazepine derivatives with 1,3-dicarbonyl reagents having active methylene group afforded the 1,2,8,9-tetrahydro-7bH-quinolino [1,2-d][1,4]benzoxazepine scaffold with different substitution pattern. The C(sp3)-H activation step of the tertiary amine moiety occurred with complete regioselectivity and the 6-endo cyclization took place in a complete diastereoselective manner. In two cases, the enantiomers of the chiral condensed new 1,4-benzoxazepine systems were separated by chiral HPLC, HPLC-ECD spectra were recorded, and absolute configurations were determined by time-dependent density functional theory- electronic circular dichroism (TDDFT-ECD) calculations. In contrast, the analogue reaction of the regioisomeric N-aryl-1,5-benzoxazepine derivative did not follow the above mechanism but instead the Knoevenagel intermediate reacted in an SEAr reaction [C(sp2)-H functionalization] resulting in a condensed acridane derivative. The AChE inhibitory assays of the new derivatives revealed that the acridane derivative had a 6.98 μM IC50 value.

Selection of Structural Features for the Systematic Study of Guided Wave Propagation and Interaction with Damage

2015 ◽  
Author(s):  
PIERRE-CLAUDE OSTIGUY ◽  
MOHAMMAD SHERAFAT ◽  
DEMARTONNE FRANCA ◽  
NIDHAL BOUSLAMA ◽  
NICOLAS QUAEGEBEUR ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Systematic Study ◽  
Structural Features ◽  
Guided Wave ◽  
Guided Wave Propagation ◽  
Selection Of

scholarly journals Structural Features Defining NF-κB Inhibition by Lignan-Inspired Benzofurans and Benzothiophenes

Biomolecules ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1131
Author(s):  
Toan Dao-Huy ◽  
Simone Latkolik ◽  
Julia Bräuer ◽  
Andreas Pfeil ◽  
Hermann Stuppner ◽  
...  
Keyword(s):  
Significant Influence ◽  
Inhibitory Activity ◽  
Structure Activity Relationship ◽  
Structural Features ◽  
Activity Relationship ◽  
Side Chain ◽  
Side Chains ◽  
Substitution Pattern ◽  
Structure Activity

A series of 2-arylbenzofurans and 2-arylbenzothiophenes was synthesized carrying three different side chains in position five. The synthesized compounds were tested for NF-κB inhibition to establish a structure activity relationship. It was found that both, the side chain in position five and the substitution pattern of the aryl moiety in position two have a significant influence on the inhibitory activity.

Structural studies of organoboron compounds. XVI. Preparation and crystal and molecular structures of 4,4-dimethyl-2,5,5-triphenyl-1,3-dioxa-4-azonia-2-bora-5-boratacyclopentane and 4,4,5,5-tetramethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2-boratacyclopentane

1984 ◽  
Vol 62 (5) ◽  
pp. 838-844 ◽  
Author(s):  
W. Kliegel ◽  
H.-W. Motzkus ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Physical Properties ◽  
Least Squares ◽  
Steric Hindrance ◽  
Direct Methods ◽  
Structural Features ◽  
Molecular Structures ◽  
Structural Studies ◽  
Full Matrix ◽  
Space Group ◽  
Crystal And Molecular Structures

Details of the synthesis, physical properties, and molecular structures of 4,4-dimethyl-2,5,5-triphenyl-1,3-dioxa-4-azonia-2-bora-5-boratacyclopentane, 4, and 4,4,5,5-tetramethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2-boratacyclopentane, 5, are reported. Crystals of 4 are triclinic, a = 9.841(2), b = 14.722(3), c = 6.6701(12) Å, α = 86.79(1), β = 102.95(1), γ = 93.89(1)°, Z = 2, space group [Formula: see text]; and those of 5 are monoclinic, a = 14.9164(12), b = 6.4732(3), c = 18.2248(15) Å, β = 117.263(3)°, Z = 4, space group Cc. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to final R values of 0.032 and 0.035 for 1456 and 1649 observed reflections, respectively. Molecules of 4 contain non-planar BOBON rings with an unusually long N(sp3)—B(sp3) distance of 1.728(3) Å and in 5 there is a long N(sp3)—C(sp3) bond of 1.591(3) Å. These structural features are ascribed to steric hindrance.

Octasolketal-substituted phthalocyanines: synthesis and systematic study of metal effect and substitution pattern on 13C NMR

2009 ◽  
Vol 13 (06) ◽  
pp. 760-768 ◽  
Author(s):  
Yunus Zorlu ◽  
Ilker Un ◽  
Fabienne Dumoulin
Keyword(s):  
Systematic Study ◽  
13C Nmr ◽  
Central Metal ◽  
Substitution Pattern ◽  
Complete Series ◽  
Metal Effect ◽  
C Nmr

A complete series of solketal octasubstituted phthalocyanines have been synthesized, with peripheral (β) or non-peripheral (α) substitution pattern. Their 13 C NMR and UV-vis properties are compared relatively to this substitution pattern or the nature of the central metal ( Ni , Zn or H 2).

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