NISCAIR Online Periodicals Repository Collection: IJC-B Vol.45B(07) [July 2006]

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

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

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

Synthesis and antibacterial activity of new oxadiazolo[1,3,5]-triazine, 1,2,4 triazolo and thiadiazolo 1,3,4 oxadiazole derivatives

Title: Synthesis and antibacterial activity of new oxadiazolo[1,3,5]-triazine, 1,2,4 triazolo and thiadiazolo 1,3,4 oxadiazole derivatives

Authors: Mulwad, V V; Chaskar, Atul C

Abstract: 3-Formyl-4-hydroxycoumarin has been treated with semicarbazide to give 4-hydroxy-2-oxo-2H[1]-benzopyran-3-aldehyde semicarbazone 1a-d, which on oxidative cyclization with bromine in glacial acetic acid in the presence of anhydrous sodium acetate gives 3-(5-amino-1,3,4-oxadiazol-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one 2a-d. 3-(5-amino-1,3,4-oxadiazol-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one on reaction with benzaldehyde gives 4-hydroxy-3-(5-benzylidine imino 1,3,4-oxadiazol-2-yl)-2H[1]-benzopyran-2-one 3a-d. 3a-d on (4+2) cycloaddition with phenyl isothiocynate gives 3-(6,7-diphenyl-5-thioxo-6,7-dihydro-5H-[1,3,4]oxadiazolo[3,2-][1,3,5]triazin-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one 4a-d. 2a-d undergoes regioselective condensation with KSCN in methanol to give N-[5-(4-hydroxy-2-oxo-2H[1]-benzopyran-3-yl)-1,3,4,-oxadiazol-2-yl]thiourea 5a-d whereas with phenyl isothiocynate it gives N-[5-(-4-hydroxy-2-oxo-2H[1]benzopyran-3-yl)-1,3,4-oxadiazole-2-yl]-N'-phenylthiourea 7a-d. 5a-d reacts with thionyl chloride in pyridine to give 4-hydroxy-3-(6-thioxo-5,6-dihydro[1,2,4]triazolo[5,1-b][1,3,4]oxadiazol-2-yl)-2H[1]-benzopyran-2-one 6a-d. 7a-d on treatment with ethanol and iodine yields 4-hydroxy-3-[6-phenylimino-6H-[1,2,4]-thiadiazolo[3,2-b][1,3,4]-oxadiazol-2-yl]-2H[1]benzopyran-2-one 8a-d.

Page(s): 1710-1715

Protonation effect on chemical shifts of some piperidones — unusual influence by anions

Title: Protonation effect on chemical shifts of some piperidones — unusual influence by anions

Authors: Manimekalai, A; Jayabharathi, J

Abstract: ¹H and ¹³C NMR spectra are recorded for twelve picrate derivatives 4-15 derived from some 3-alkyl-2,6-diarylpiperidin-4-ones and 3,5-dimethyl-2,6-diarylpiperidin-4-ones. The difference in the chemical shift of equatorial methylene proton and axial methylene proton at C(5) [ = _eq - _ax] is highly negative in 4-13 which is in contrast to the value observed in the corresponding parent piperidin-4-ones and this is attributed to the syn 1,3-diaxial interaction between the axial N-H bond and axial hydrogen at C-5. The effect of protonation on the chemical shifts was studied in detail. The chemical shifts of the heterocyclic ring protons are influenced by the picrate anion.

Page(s): 1686-1691