NOPR Collection:

Theoretical study of facial selectivity and regioselectivity in electrophilic addition reaction of chlorine to exo-tricyclo[4.2.1.0^2,5]nona-3,7-diene

Sat, 01 Jul 2006 00:00:00 GMT

Title: Theoretical study of facial selectivity and regioselectivity in electrophilic addition reaction of chlorine to exo-tricyclo[4.2.1.0^2,5]nona-3,7-diene Authors: Abbasoglu, Rza; Yilrnaz, Sevil Savaskan Abstract: For prediction and interpretation of facial selectivity and regioselectivity of the electrophilic addition reaction to exotricyclo[4.2.1.0²^,⁵]nona-3,7-diene(exoTND) of chlorine, various models(geometric distortions, electron density, orbital effects, electrostatic effects and intermediates stabilities) have been used. Full geometric optimization of exoTND molecule has been done by ab initio and DFT methods and the structure of the molecule have also been investigated. Norbornene double bond(II) of molecule is endo pyramidalized and cyclobuten double bond(II) is also syn pyramidalized. The double bond(I) is more pyramidalized than the double bond(III) and it has higher reactivity. Exo face of the double bond(I) and anti face of the double bond(II) of the molecule are regions having much more electron density(qi,_HOMO) and bigger negative potential. The exoTND-Cl₂ system has been investigated by B3LYP/6-311+G* method and their stable configurations have been determined. The exoTND ... Cl₂) and exoTND ... Cl₂(anti) molecular complexes correspond to the most stable configurations of exoTND-Cl₂ system. The most stable configuration of bridged cationic intermediates is the exo-bridged chloronium cation. The results that are obtained by using the models for predicted and interpredicted facial selectivity and regioselectivity of the electrophilic addition reaction of chlorine to exoTND molecule agree with each other. Facial selectivity and regioselectivity of the addition reaction parallel the pyramidalization of the double bond. Page(s): 1722-1728

2,3-Diphenyltetrahydrofurans (DPTF) - A new class of stereogenic diarylheterocycles as potential COX-2 inhibitors - Computational evaluation of COX-2-DPTF binding behaviour

Sat, 01 Jul 2006 00:00:00 GMT

Title: 2,3-Diphenyltetrahydrofurans (DPTF) - A new class of stereogenic diarylheterocycles as potential COX-2 inhibitors - Computational evaluation of COX-2-DPTF binding behaviour Authors: Singh, Palwinder; Kaur, Pervinder; Anu; Kumar, Subodh Abstract: Based on the reported COX-2 selectivity of α,β-diarylheterocycles based NSAIDs' - a new class of 2,3-diphenyltetrahydrofurans (DPTF) possessing COOH, CH₂OH or CH₂NH₂ groups at C-5 and three chiral centers C-2, C-3 and C-5 have been designed. In total 12 title compounds have been studied for their binding in the active sites of COX-2 and COX-1 enzymes. For comparison, the binding behavior of known COX-2 selective (rofecoxib, celecoxib, valdecoxib) and nonselective (aspirin, ibuprofen) drugs has also been studied. The trends of COX-2 selectivity of known NSAIDs' are parallel with their reported results. In general, DPTF derivatives show binding energies in COX-2 active site better than rofecoxib and comparable to aspirin and poor binding energies in COX-1 active sites pointing towards these molecules being selective COX-2 inhibitors. The stereochemistries at C-2, C-3 and C-5 carbons of DPTF derivatives considerably affect their bindings in the active sites of COX-1 and COX-2 and the COX-2 selectivity. The ligands with configuration (2S, 3R, 5S) show higher selectivity for COX-2 over COX-1 in comparison to other configurational isomers. Page(s): 1692-1698

Isomerization of the Baylis-Hillman adducts using amberlyst-15 as a heterogeneous reusable catalyst: a simple and efficient stereoselective synthesis of (E)-cinnamyl alcohol derivatives

Sat, 01 Jul 2006 00:00:00 GMT

Title: Isomerization of the Baylis-Hillman adducts using amberlyst-15 as a heterogeneous reusable catalyst: a simple and efficient stereoselective synthesis of (E)-cinnamyl alcohol derivatives Authors: Das, Biswanath; Banerjee, Joydeep; Majhi, Anjoy; Chowdhury, Nikhil; Venkateswarlu, Katta; Holla, Harish Abstract: The Baylis-Hillman adducts, 3-aryl-3-hydroxy-2-methylene-alkanoates and 3-aryl-3-hydroxy-2-methylene-alkanenitriles have been efficiently isomerized to the corresponding (E)-cinnamyl alcohols by treatment of the adducts with Ac₂O in the presence of Amberlyst-15 followed by hydrolysis of the intermediate acetates with K₂CO₃/MeOH. The first step occurs under solvent-free conditions and the catalyst has been found to be reusable. Page(s): 1729-1733

Synthesis and studies of novel homoveratryl based thiohydantoins as antibacterial as well as anti-HIV agents

Sat, 01 Jul 2006 00:00:00 GMT

Title: Synthesis and studies of novel homoveratryl based thiohydantoins as antibacterial as well as anti-HIV agents Authors: Patel, R B; Desai, K R; Chikhalia, K H Abstract: N,N′-bis(3,4-dimethoxyphenylethyl)-5-(arylidene)-2-thiohydantoins 3a-j have been prepared by condensation of 1,3-diaryl-2-thiohydantoin 2 with various aromatic aldehydes. The compound 2 has been prepared by the reaction of N,N′-bis(3,4-dimethoxyphenylethyl)thiourea 1 with chloroaceticacid. The compounds have been tested for their antibacterial and anti-HIV activities against different microorganisms. The structures of novel synthesized compounds have been established on the basis of elemental analyses, ¹H NMR, IR and mass spectral data. Page(s): 1716-1721

NOPR Collection:

Theoretical study of facial selectivity and regioselectivity in electrophilic addition reaction of chlorine to exo-tricyclo[4.2.1.02,5]nona-3,7-diene

2,3-Diphenyltetrahydrofurans (DPTF) - A new class of stereogenic diarylheterocycles as potential COX-2 inhibitors - Computational evaluation of COX-2-DPTF binding behaviour

Isomerization of the Baylis-Hillman adducts using amberlyst-15 as a heterogeneous reusable catalyst: a simple and efficient stereoselective synthesis of (E)-cinnamyl alcohol derivatives

Synthesis and studies of novel homoveratryl based thiohydantoins as antibacterial as well as anti-HIV agents

Theoretical study of facial selectivity and regioselectivity in electrophilic addition reaction of chlorine to exo-tricyclo[4.2.1.0^2,5]nona-3,7-diene