نتایج جستجو برای: ring substitution

تعداد نتایج: 177743  

Chalcone (1,3-diarylprop-2-en-1-one) derivatives have been introduced as selective cyclooxygenase-2 inhibitors. In the present study, anti-nociceptive and anti-inflammatory effects of eight novel compounds were evaluated in male mice and Wistar rats by using the writhing and formalin-induced paw edema tests respectively. The activities of the compounds were compared with celecoxib as a referenc...

1999
Hasan Palandoken Justin K. Wyatt Shawn R. Hitchcock Marilyn M. Olmstead Michael H. Nantz

New examples of ansa-titanocenes derived from 1,2-bis(2-indenyl)ethane have been prepared. The titanium-mediated reductive coupling of 2-(hydroxymethyl)indenes provided a convenient method for substrate dimerization. Alkyl substitution of the indene ring at C(3) improved the regioselectivity of the reductive coupling to provide the ethylene bis(2-indenyl)ansa-ligands in 29–62% yield.

2009
Ramakrishna Gowda Ganesh N. Alawandi Manohar V. Kulkarni K. V. Arjuna Gowda

The crystal structure of the title compound, C(11)H(7)BrN(2)O(6), establishes the substitution positions of the nitro groups from the nitration reaction of 7-methyl-4-bromo-methyl coumarin. The mean planes of the nitro groups form dihedral angles of 43.9 (8) and 52.7 (10)° with the essentially planar [maximum deviation 0.031 (6) Å] benzopyran ring system.

2010
Graham Pattison Graham Sandford Dmitrii S Yufit Judith A K Howard John A Christopher David D Miller

Reaction of tetrafluoropyridazine with catechol gives a tricyclic 9,10-dioxa-1,2-diaza-anthracene system by a sequential nucleophilic aromatic substitution ring annelation process, further extending the use of perfluoroheteroaromatic derivatives for the synthesis of unusual polyfunctional heterocyclic architectures. The tricyclic scaffold reacts with amines and sodium ethoxide providing a short...

Journal: :RSC advances 2015
Xiang Sun Yunwei Chen Ningjie Wu Chi Soo Kang Hyun A Song Shengnan Jin Yao Fu Henry Bryant Joseph A Frank Hyun-Soon Chong

Ring opening of aziridinium ions with nitrogen nucleophiles was applied to the highly efficient synthesis of optically active vicinal diamines and diethylene triamine pentaacetic acid (DTPA) analogues as potential magnetic resonance imaging (MRI) contrast enhancement agents. The synthetic method features a column-free isolation of the regiospecific and stereospecific nucleophilic substitution p...

2014
Laura G Sarbu Henning Hopf Peter G Jones Lucian M Birsa

An addition/elimination sequence of selenium halides to pseudo-geminally bis(acetylene) substituted [2.2]paracyclophanes leads to new bridges with an endo-exo-diene substructure. The reactions have been found to be sensitive to the substitution of the ethynyl group. The formation of dienes with a zig-zag configuration is related to that observed for non-conjugated cyclic diynes of medium ring s...

2015
Homar S. Barcena Peishan Chen Abraham Tuachi

Anthocyanidins were synthesized to study the effect of methoxy substitution on the B ring to their antioxidant property. Comparative FRAP studies show 2'- and 4'-methoxy substituents have higher antioxidant activities, which may be attributed to both resonance and inductive effects.Graphical abstract:Anthocyanidins as reducing agents.

Journal: :Organic & biomolecular chemistry 2012
Marco V Mijangos Joaquin González-Marrero Luis D Miranda Paulette Vincent-Ruz Armando Lujan-Montelongo Diana Olivera-Díaz Elhiu Bautista Alfredo Ortega María de la Luz Campos-González Rocio Gamez-Montaño

Flavones were directly alkylated at the C-3 position in moderate yields using a xanthate-based oxidative radical addition procedure. This methodology is a suitable synthetic tool for the direct substitution of the vinylic and unactivated C-H bond of the C ring of the flavone by an alkyl functionality under neutral conditions.

Journal: :Chemical communications 2014
Naveen R Rondla Jodi M Ogilvie Zhongda Pan Christopher J Douglas

Reported here is a palladium catalyzed intramolecular acylcyanation of alkenes using α-iminonitriles. Through this method, highly functionalized indanones are synthesized in moderate to high yields using Pd(PPh3)4, without need for any additional ligands, and a common Lewis acid (ZnCl2). Additionally, the reaction tolerates substitution at various positions on the aromatic ring including electr...

Journal: :IACR Cryptology ePrint Archive 2015
Juan Carlos Ku-Cauich Guillermo Morales-Luna Horacio Tapia-Recillas

Two new systematic authentication code based on the Gray map over a Galois ring are introduced. The first introduced code attains optimal impersonation and substitution probabilities. The second code improves space sizes but it does not attain optimal probabilities. Besides it is conditioned to the existence of a special class of bent maps on Galois rings.

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید