- Quantitative structure-activity relationship studies for prediction of antimicrobial activity of synthesized 2,4-hexadienoic acid derivatives
-
A new series of 2,4-hexadienoic acid derivatives (S1-S42) has been synthesized and evaluated as antimicrobial agents against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans, and Aspergillus niger. Quantitative structure-activity relationship (QSAR) investigation using Hansch analysis was applied to find out correlation between antimicrobial activities with physicochemical properties of the synthesized compounds. Various physicochemical descriptors and experimentally determined minimum inhibitory concentration values for different microorganisms were used as independent and dependent variables, respectively. The QSAR revealed that topological parameters especially molecular connectivity indices (χ2, 0χv, 2χv) were found to have overall significant correlation with antimicrobial activity of 2,4-hexadienoic acid derivatives. The statistical results of training set, cross-validated r2 and conventional r values gave reliability to the prediction of molecules with activity using QSAR models.
- Narasimhan, Balasubramanian,Judge, Vikramjeet,Narang, Rakesh,Ohlan, Ruchita,Ohlan, Sucheta
-
p. 5836 - 5845
(2008/03/18)
-
- DBU-mediated Ireland-Claisen rearrangement of allyl alk-3-enoates: an efficient synthesis of 2-ethylidene-γ,δ-unsaturated carboxylic acids
-
Ireland-Claisen rearrangement, triggered by silyl enolization of allylic but-3-enoates 2, has been developed using DBU as the base in the presence of an excess amount of TMSCl under reflux in acetonitrile for a couple of hours. The procedure allows the synthesis of a range of 2-ethylidene-γ,δ-unsaturated carboxylic acids 5 in moderate to high yields. It is further revealed that the rearrangement proceeds equally well with allylic (E)-hexa-3,5-dienoates 10 derived from sorbic acid under similar conditions to provide 2-allyl substituted hexa-2,4-dienoic acids 13.
- Li, Yunxia,Goeke, Andreas,Wang, Ruiyao,Wang, Quanrui,Fráter, Georg
-
p. 9605 - 9613
(2008/02/11)
-
- Reinvestigation on the Catalytic Isomerisation of Carbon-Carbon Triple Bonds
-
Based on the discovery that phosphines could catalyse the isomerisation of triple bonds, the isomerisation of acetylenic derivatives was differentiated into two types: phosphine-catalysed and transition metal-catalysed.
- Guo, Cheng,Lu, Xiyan
-
p. 1921 - 1924
(2007/10/02)
-
- Phase-Transfer Catalyzed Synthesis of 2-Propenyl Esters of Carboxylic Acids
-
The tetrabutylammonium bromide catalyzed esterification of salts of carboxylic acids 1 a-e with 2-propenyl halides 2 a, b is described.Keywords.Esterification; Phase-transfer catalysis; 2-Propenyl esters.
- Klan, Petr,Benovsky, Petr
-
p. 469 - 472
(2007/10/02)
-
- Aspects of the Intramolecular Diels-Alder Reactions of Some 1,3,9-Trienic Amides, Amines, and Esters. An Approach to the Pentacyclic Skeleton of the Yohimboid Alkaloids
-
The intramolecular cycloadditions of a number of 1,3,9-tienes containing an amide, amine, or ester function in the chain linking the dienophile and the diene were examined, and a general preference for the formation of cis cycloadducts was observed.Thus, the aza trienes 7b-h were found to undergo intramolecular Diels-Alder reaction upon thermolysis at temperatures ranging from 25 to 275 deg C to give mixtures of the cis- and trans-hydroisoquinolines 9b-h and 10b-h, respectively, in ratios that varied from about 1.1:1 to 8:1.Thermolysis of the pentadienamide 34 produced the cis- and trans-hydroisoquinolines 35 and 36 (1.6:1).Interestingly, the aza trienes 13 and 14 in which the internal double bond is Z appear to suffer extensive isomerization, presumably via 1,5-hydrogen migration, prior to cyclization to provide isomeric trienes, which have not been isolated but have been tentatively identified as 22 and 25 since they afford corresponding mixtures of the cis- and trans-hydroisoindoles 20/21 and 23/24 as the principle cycloadducts; only small amounts of the expected cis-hydroisoquinolines 9e and 9h were obtained in these thermolyses.In order to demonstrate the feasibility of applying intramolecular Diels-Alder reactions of aza trienes to the syntheses of alkaloids containing a hydroisoquinoline ring, the trans-hydroisoquinoline 10d was converted to the yohimbine-related compounds 38 and 39 by cyclization with POCl3 followed by either catalytic hydrogenatin or hydride reduction of the intermediate iminium salt.The reactivity of the related esters 40-42 toward intramolecular cycloaddition was also briefly examined, and it was found that only the acrylate 41 underwent cyclization at temperatures below 275 deg C.
- Martin, Stephen F.,Williamson, Sidney A.,Gist, R. P.,Smith, Karl M.
-
p. 5170 - 5180
(2007/10/02)
-