Microwave Activated Solid Support Synthesis of New Antibacterial Quinolones

Summary.  A novel synthesis of 6-fluoro-7-(5-aryl-1,3,4-thiadiazol/oxadiazol-2-yl-sulfanyl)-4-quinolone-3-carboxylic acids from 7-chloro-6-fluoro-4-quinolone-3-carboxylic acid and 5-substituted 1,3,4-thiadiazoles/oxadiazoles on basic alumina under microwave activation is described. All compounds were screened for their in vitro antibacterial activity against B. lichenformis, 2689, K. aerogens 2281, S. typhimurium 2501, E. herbicola 2491, and P. vulgaris 2027 and found to possess activities comparable to that of the standard drug norfloxacin. Received May 2, 2000. Accepted (revised) June 13, 2000     

Microwave-Assisted Solid-Phase Synthesis of Cephalosporin Derivatives with Antibacterial Activity

 The reaction of heterocyclic acids with 7-amino-cephalosporanic acid adsorbed on basic alumina under microwave irradiation afforded the N-acylated cephalosporin analogues in satisfactory yield. All compounds were tested for their antibacterial activity; some of them showed significant antibacterial properties. Cefotaxime and cephalothin were used as reference drugs.     

An Efficient Microwave-Assisted Synthesis of Structurally Diverse Styrylquinolines

Summary. Aromatic aldehydes undergo condensation with quinaldines under microwave irradiation to afford structurally diverse styrylquinolines in high yields under solvent-free conditions. A comparison with the conventional method clearly indicates the advantages of the new protocol.     

Synthesis, Characterization, and Antibacterial Activity of Complexes of (1S,2S)-N,N-1,2-Diphenylethylene-bis-(5-imino-1-phenyl-1,3-hexanedione)

Summary.  The synthesis and characterization of homobimetallic complexes of VO(IV), Cr(II), Co(II), Ni(II), and Cu(II) with the chiral Schiff base (1S,2S)-N,N-1,2-Diphenylethylene-bis-(5-imino-1-phenyl-1,3-hexa-nedione) is reported. The metal ions occupy both compartments of the ligand; water molecules fill the coordination spheres to provide an octahedral environment around the central atoms. The antibacterial activity of both mono- and bimetallic complexes against a number of Gram-positive as well as Gram-negative bacteria has been tested and is discussed. Received March 28, 2000. Accepted May 26, 2000     

New 6-(4-Bromophenyl)-imidazo[2,1-b]thiazole Derivatives: Synthesis and Antimicrobial Activity

Summary.  New 4-alkyl/aryl-1-((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-3-thiosemicarbazides and 3-alkyl/aryl-2-(((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-hydrazono)-4-thiazolidinones were synthesized from 6-(4-bromophenyl)-imidazo[2,1-b]thiazole-3-acetic acid hydrazide. Their structures were elucidated by elemental analyses and spectroscopic data. All compounds were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by the microbroth dilution technique. The compounds were also evaluated for antituberculosis activity against Mycobacterium tuberculosis H₃₇Rv (ATCC 27294); they exhibited varying degrees of inhibition in the in vitro primary screening at 6.25 μg · cm⁻³. The most active compound was 3-(4-nitrophenyl)-2-(((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-hydrazono)-4-thiazolidinone. Corresponding author. E-mail: nurayulusoy@yahoo.com Received December 10, 2001. Accepted (revised) March 1, 2002     

Synthesis and Hemolytic Properties of Lactosides of Glycyrrhetic Acid Derivatives

Summary.  The partial synthesis of lactosides of glycyrrhetic acid, its 11-deoxo and 18α-derivatives, and their methyl esters is described. The influence of the aglycon structure on the hemolytic properties of the title compounds is discussed and compared with those of oleanolic acid derivatives. Furthermore, we describe an optimized preparation of 18α-glycyrrhetic acid. Received August 20, 2001. Accepted September 3, 2001     

Synthesis and Antibacterial Activity of Oxazolidinone Derivatives Containing Nitro Heteroaromatic Moiety

A series of novel oxazolidinone derivatives containing nitro heteroaromatic moiety was synthesized and characterized by means of ¹H NMR and MS spectra. All target compounds were evaluated for their in vitro antibacterial activities against S.au 29213, methicillin-resistant Staphylococcus aureus(MRSA) and vancomycin-resistant Enterococcus(VRE) by minimum inhibitory concentration(MIC) assay. Most of them exhibited antibacterial activity against S. au 29213, MRSA and VRE. Among them, compounds 10e and 10f displayed better activity than the control.     

Synthesis, Characterization, and Biological Activity of n-Tributyltin Derivatives of Pharmaceutically Active Carboxylates

Summary.  Tributyltin(IV) derivatives of six different pharmaceutically active carboxylates were synthesized. The complexes were characterized by different analytical techniques (elemental analysis; infrared, NMR, and mass spectroscopy). ¹¹⁹Sn NMR data were also recorded in six different coordinating and non-coordinating solvents. The antibacterial activities of the compounds were tested using ten different bacteria relative to the reference drugs ampicillin and cephalexin. Received September 20, 2001. Accepted (revised) December 6, 2001     

Alumina Catalyzed Synthesis of Fused Thioxopyrimidine Derivatives Under Microwaves

Abstract

An expeditious solventless approach for the synthesis of pyrazolino[3,4-d]/isoxazolino[3,4-d]/pyrano[2,3-d]/iminopyrimidino[4,5-d]/thioxopyrimidino[4,5-d]/thiazino[5,4-d] pyrimidines from 2-thiobarbituric acid using supported reagents (acidic/basic alumina) under microwave irradiation (MWI) is described. The reaction times were brought down from hours to minutes with yield enhancement. Also the procedure highlights the versatility of solid supports.     

Synthesis,Characterization and Antibacterial Activity of New 5-Aryl Pyrazole Oxime Ester Derivatives

Eleven new 1-{5-[4-（benzyloxy）phenyl]-3-methyl-4,5-dihydropyrazol-l-yl} oxime ester dcrivatives were synthesized and characterized by elemental analysis, HRMS, ^1H NMR data. All the compounds were screened for their antibacterial potential in vitro against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The results indicate that compounds 8c and 8f possess potent activity with the minimum inhibitory concentrations（MIC） of 1.562--3.125 ug/mL against all the four bacteria. Compounds 8c, 8e and 8f show moderate inhibition against the DNA gyrase（IC50=1.9--2.5 ug/mL）. On the basis of the biological activities, structure-activity relationship was discussed.     

Solid State Desemicarbazonation on Clayfen Under Microwave Irradiation

Summary.  A new, efficient, and environmentally benign method for the cleavage of semicarbazones has been achieved by a simple reaction of semicarbazones with clayfen under microwave irradiation. Received January 4, 2001. Accepted (revised) March 1, 2001     

Synthesis and Antibacterial Activity of New Cephalosporin Compounds

The fourth generation cephalosporin cefepime I exhibited potent antibacterial activity with board antibacterial spectrum1,2.Based on the structure of cefepime,we synthesized its analogs Ia having fluoro atom at the aminothiazolyl oxime moiety at the7-position of the cephem nucleus,and Ib possessing1-(2-fluoroethyl)pyrrolidium methyl group at the3-position.It was reported that cephalosporin derivatives with a quaternary ammonium moiety at the3-position of the cephem nucleus,showed enhanced ant…     

Synthesis and Antiinflammatoryand Anticancer Activity Evaluation of Some Condensed Pyrimidines

Summary.  Upon condensation with 4-isothiocyanato-4-methyl-2-pentanone, 2,3-diaminonaphthalene and N-aminoethyladenosine gave in good yields substituted pyrimidonaphthoimidazole and imidazopyrimidine thione. Refluxing pyrimidobenzthiazole with methanol H₂SO₄ at pH∼1 resulted in S-methyl pyrimidobenzthiazole in moderate yield. Pyrimidobenzimidazole derivatives could be reacted to S-alkylated and N-acylated derivatives by refluxing with ethyl bromoacetate in the presence of anhydrous potassium carbonate in THF and by heating in an acetic acid/acetic anhydride mixture. Heating of pyrimidobenzimidazole with 75% aqueous H₂SO₄ on a water bath ended up in a rearranged product. All compounds gave correct ¹H NMR, IR, and HR mass spectra. Results of antiinflammatory, analgesic, and anticancer activity screening of the new compounds are described. Received October 29, 1999. Accepted (revised) January 13, 2000     

吲哚-6-酰腙类化合物的微波合成及其抗菌活性研究

把酰腙类结构引入吲哚环中, 合成一类新型的吲哚-6-酰腙化合物, 以期为新药筛选提供先导化合物. 在微波辐射条件下, 以较高的产率得到14个未见报道的新化合物, 其结构均经1H NMR, IR, MS及元素分析确证, 并测试了化合物的抑菌活性.     

无溶剂研磨法合成3-取代色满-4-酮衍生物及其抑菌活性研究

以6-卤代或未取代色满-4-酮为原料,在碱催化的条件下采用无溶剂研磨法与醛发生缩合反应,合成一系列新型的3-取代色满-4-酮衍生物3a~3t,并通过IR、1H NMR、13C NMR、HRMS对所合成的化合物进行结构表征。抑菌活性测试结果表明,所合成的化合物对大肠杆菌、枯草杆菌、金黄色葡萄球菌均有不同程度的抑菌活性。     

2-氨基噻唑缩取代水杨醛Zn(Ⅱ)配合物的合成、表征及抑菌活性

合成了４个２－氨基噻唑缩取代水杨醛Ｚｎ（Ⅱ）的配合物,通过元素分析,ＩＲ,１ＨＮＭＲ及ＵＶ－ｖｉｓ光谱进行了结构表征。抑菌实验结果表明,配合物的活性优于配体     

One-Pot Synthesis of N-Substituted 4-Aryl-1,4-dihydropyridines Under Solvent-Free Conditions and Microwave Irradiation

Summary.  The three-component condensation of benzaldehyde derivatives, alkyl propiolates, and primary amines catalyzed by silica gel, zeolite HY, montmorillonite K-10, and acidic alumina under microwave irradiation gave N-substituted 4-aryl-1,4-dihydropyridines in short reaction times and high yields. The best results were obtained with silica gel. Received March 26, 2001. Accepted (revised) June 18, 2001     

Synthesis and Antibacterial Evaluation of Novel 3,6-Disubstituted Coumarin Derivatives

A novel series of 3,6-disubstituted coumarin derivatives were synthesized by the reaction of ethyl-2-(3-acetyl-2-oxo-2H-chromen-6-yl)-4-methylthiazole-5-carboxylate with thiosemicarbazide and various phenacyl bromides / 3-(2-bromoacetyl)-2H-chromen-2-ones / 2-(2-bromoacetyl)-3H-benzo[f]chromen-3-one in ethanol having catalytic amount of acetic acid under reflux conditions with good yields. All the synthesized compounds were fully characterized by spectral studies and evaluated for their in vitro antibacterial activity against Pseudomonas aeruginosa, Bacillus subtilis (Gram positive), Escherichia coli, and Azatobacter (Gram negative) bacterial strains. Activity results revealed that the compound 6h against Escherichia coli and compound 6i against Pseudomonas aeruginosa and Escherichia coli have shown maximum zones of inhibition. Remaining compounds showed moderate to good activity against all the tested bacterial strains compared with the standard drug cefotaxime.     

稀土三元配合物的低热固相合成、表征及抑菌活性研究

首次在室温条件下通过固相反应制得了镧稀土水杨酸8-羟基喹啉三元配合物La(Hsal)2(hq)(hq=C9H6NO^-;Hsal^-=C7H5COO^-)。采用元素分析、红外光谱、X射线粉末衍射、热重-差热分析等手段对配合物进行了表征。同时还初步分析了固相反应的机理。抑菌实验表明该配合物对大肠杆菌、金黄色葡萄球菌、白色念珠菌、芽孢杆菌都有很好的抑菌效果。     

新型芳基吡唑衍生物的合成及其抑菌活性

以2,4-二氯苯甲醛和丙酮为原料,经缩合,环合和取代反应,首次合成了7个未见文献报道的5-(2,4-二氯苯基)-3-甲基-4,5-二氢-N-酰基吡唑类衍生物,其结构经1H NMR,IR和元素分析表征。初步的生物活性测试结果表明,部分化合物具有一定的杀菌活性。