Synthesis and Antimicrobial,Anticancer and Anti-Oxidant Activities of Novel 2,3-Dihydropyrido[2,3-d]pyrimidine-4-one and Pyrrolo[2,1-b][1,3]benzothiazole Derivatives via Microwave-Assisted Synthesis

In our attempt towards the synthesis and development of effective antimicrobial, anticancer and antioxidant agents, a novel series of 2,3-dihydropyrido[2,3-d]pyrimidin-4-one 7a–e and pyrrolo[2,1-b][1,3]benzothiazoles 9a–e were synthesized. The synthesis of 2-(1,3-benzo thiazol-2-yl)-3-(aryl)prop-2-enenitrile (5a–e) as the key intermediate was accomplished by a microwave efficient method. Via a new variety oriented synthetic microwave pathway, these highly functionalized building blocks allowed access to numerous fused heteroaromatic such as 7-amino-6-(1,3-benzo thiazol-2-yl)-5-(aryl)-2-thioxo-2,3dihydropyrido [2,3-d]pyrimidin-4(1H)-one 7a–e and 1-amino-2-(aryl)pyrrolo[2,1-b][1,3]benzothiazole-3-carbonitrile derivatives 9a–e in order to study their antimicrobial and anticancer activity. The present investigation offers effective and rapid new procedures for the synthesis of the newly polycondensed heterocyclic ring systems. All the newly synthesized compounds were evaluated for antimicrobial, anticancer and antioxidant activity. Compounds 7a,d, and 9a,d showed higher antimicrobial activity than cefotaxime and fluconazole while the remaining compounds exhibited good to moderate activity against bacteria and fungi. An anticancer evaluation of the newly synthesized compounds against the three tumor cell lines (lung cell NCI-H460, liver cancer HepG2 and colon cancer HCT-116) exhibited that compounds 7a, d, and 9a,d have higher cytotoxicity against the three human cell lines compared to doxorubicin as a reference drug. These compounds also exhibited higher antioxidant activity and a great ability to protect DNA from damage induced by bleomycin.     

Synthetic cephalosporins. VII. Synthesis and antibacterial activity of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(3-(3-hydroxy-4-pyridon-1-yl)-3- carboxypropoxyimino)acetamido]-3-(1,2,3-thiadiazol-5-yl)-thiomethyl-3- cephem-4-carboxylic acid and its related compounds

Synthesis and antibacterial activity of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(3-(3-hydroxy-4-pyridon-1-y l)-3- carboxypropoxyimino)acetamido]-3-(1,2,3-thiadiazol-5-yl)thio methyl-3-cephem-4-carboxylic acid (12a) and its related compounds are described. Compound 12a exhibited excellent antibacterial activity against gram-negative bacteria, including Pseudomonas aeruginosa.     

Synthesis and microbial screening of 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives

The present investigation describe the synthesis of 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives. Quinolin-8-ol was transformed by five step synthetic procedures into 8-Benzyloxy-5-(2-bromo-acetyl)-1H-quinolin-2-one. Subsequently, 8-Benzyloxy-5-(2-bromo-acetyl)-1H-quinolin-2-one condensed with 1,3-Diphenyl-1H-pyrazole-4-carbothioic acid amide in the presence of acetonitrile to afford 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives. Synthesized compounds were screened for their antimicrobial activity against gram-positive and gram-negative bacteria. Most of the synthesized compounds are found to be active against tested bacterial strains and fungal strain.     

2-(Benzo[d]thiazol-2-yl) phenyl-4-nitrophenyl alkyl/aryl substituted phosphoramidates: Synthesis,characterization and antimicrobial activity evaluation

A series of new 2-(benzo[d]thiazol-2-yl) phenyl-4-nitrophenyl alkyl/aryl substituted phosphoramidate derivatives (7a-j) of biological interest are synthesized in two steps via an in situ process without the isolation of the intermediate. 2-(Benzo[d]thiazol-2-yl) phenol (3) was treated with 4-nitrophenyl phosphorodichloridate(4) to obtain the monochloro intermediate, 2-(benzo[d]thiazol-2-yl)phenyl (4-nitrophenyl) phosphorochloridate(5). It was subsequently reacted with various amines, 6(a-j) to afford the desired title products. IR, NMR (¹H, ¹³C and ³¹P), mass spectral and elemental analysis are used to characterize the structures of the newly synthesized compounds. The antibacterial and antifungal activities are determined by the growth of inhibition of bacteria and fungi of the title compounds at two concentrations, 50 and 100 µg/mL, and minimum inhibitory concentrations to the active compounds. The compounds 7e, 7f and 7j exhibited promising inhibition activity against bacterial strains and 7c, 7e and 7i against A. niger and C. albicans and MIC values are in the range of 10.0–15.0 µg/mL.     

Synthesis of Some New Thiazoles and Pyrazolo[1,5-a]pyrimidines Containing an Antipyrine Moiety

Ethyl 2-{2-[4-(2,3-dimethyl-5-oxo-1-phenyl-3-(pyrazolin-4-yl)]-2-cyano-1-(phenylamino)vinylthio}-acetate, 2-[4-(2,3-dimethyl-5-oxo-1-phenyl-(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]2-(4-oxo-3-phenyl-(1,3-thiazoilidin-2-ylidene))ethanenitrile, 2-[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]-2-(4-methyl-3-phenyl(1,3-thiazolin-2-ylidene))ethanenitrile, 2-(5-acetyl-4-methyl-3-phenyl(1,3-thiazolin-2-ylidene))-2-[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]ethanenitrile, and ethyl 2-(cyano(4-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)thiazol-2-yl)methylene)-2,3-dihydro-4-methyl-3-phenylthiazole-5-carboxylate were synthesized by treatment of 2-(4-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)thiazol-2-yl)-3-mercapto-3-(phenylamino)-acrylonitrile with appropriate halo ketones or halo esters. Also, 4-{2-[5,7-dimethyl-2-(phenylamino)(7a-hydropyrazolo[1,5-a]pyrimidin-3-yl](1,-thiazol-4-yl)}-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one derivatives were synthesized via reaction of 4-{2-[5-amino-3-(phenylamino)pyrazolin-4-yl](1,3-thiazol-2-yl)}-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one with β-diketone or β-keto ester. All synthesized compound were established by elemental analysis, spectral data, and alternative synthesis whenever possible.     

2-[4-(2,6-二氟苯基)噻唑-2-基]-3-羟基丙烯腈衍生物的合成及生物活性

为了寻找生物活性良好的噻唑基丙烯腈类化合物, 利用2-[4-(2,6-二氟苯基)噻唑-2-基]乙腈(3)分别与取代氯甲酸酯4和取代苯基异氰酸酯6在碱存在下反应, 合成了8个2-[4-(2,6-二氟苯基)噻唑-2-基]-3-羟基-3-烃氧基丙烯腈化合物5和7个2-[4-(2,6-二氟苯基)噻唑-2-基]-3-羟基-3-取代苯胺基丙烯腈化合物7, 均为首次报道的丙烯腈类化合物. 化合物结构经1H NMR, IR, MS和元素分析表征. 初步生物活性测定结果表明, 在试验浓度下, 目标化合物均具有一定的杀虫和抑菌活性, 其中化合物5f和5h在100 mg/L浓度下对炭疽病菌的抑制率达95%; 化合物5g和7d在250 mg/L浓度下对棉红蜘蛛的致死率达85%.     

Synthesis and antibacterial activity of new N-[2-(thiophen-3-yl)ethyl] piperazinyl quinolones

As a part of continuing search for potential antibacterial agents in the quinolones field, we have synthesized novel quinolone agents bearing N-[2-(thiophen-3-yl)ethyl] piperazinyl moiety in the 7-position of the quinolone ring. In vitro antibacterial evaluation of the target compounds showed that N-[2-(thiophen-3-yl)ethyl] group attached to piperazine ring served as promising C-7 substituent for piperazinyl quinolone antibacterials. Among these derivatives, ciprofloxacin analogues, containing N-[2-(thiophen-3-yl)-2-hydroxyiminoethyl] or N-[2-(thiophen-3-yl)-2-methoxyiminoethyl] residue provided a high inhibition against all the tested Gram-positive organisms including methicillin-resistant Staphylococcus aureus comparable or superior with respect to the reference drugs norfloxacin and ciprofloxacin.     

SYNTHESIS AND CHEMISTRY OF SOME NEW 2-MERCAPTOIMIDAZOLE DERIVATIVES OF POSSIBLE ANTIMICROBIAL ACTIVITY

4,5-Diaryl-2,3-dihydro-2-mercaptoimidazoles (2a–e) were synthesized. They reacted with chloroacetic acid in gl. acetic acid/Ac ₂ O in presence of anhyd. sodium acetate afforded 5,6-diaryl-2,3-dihydro-imidazo[2,1-b]thiazol-3-ones (3a–d). Also these compounds were prepared by the action of chloroacetyl chloride on compounds (2) in pyridine. Compounds (3a–d) on condensation with aromatic aldehydes yield 2-arylmethylene-5,6-diaryl-2,3-dihydroimidazo[2,1-b]-thiazol-3-ones (4a–q). The latter compounds were prepared directly by the reaction of (2) with chloroacetic acid and the aromatic aldehydes. Compounds (3a–d) coupled with aryldiazonium salts in pyridine to give 2-arylhydrazono-5,6-diaryl-2,3-dihydroimidazo[2,1-b]thiazol-3-ones (5a–r). Also compounds (2) when reacted with 2 or 3-bromopropionic acid afford 2,3-di-hydro-5,6-diaryl-2-methylimidazo[2,1-b]thiazol-3-ones (6a–d) and 2,3-di-hydro-6,7-diaryl imidazo-[2,1-b]-1,3-thiazin-4-ones (7a–d), respectively. Compounds (3, 6, and 7) have been cleaved by aromatic amines to give the corresponding 2-(4′,5′-diaryl-2′,3′-dihydroimidazol-2′-yl)thioacetanilide (8a–f), 2-(2′,3′-dihydro-4′,5′-diaryl imidazol-2′-yl)thiopropionamide (9a–c), and 3-(2′,3′-dihydro-4′,5′-diaryl-imidazol-2′-yl)thiopropionamide (10a–d) respectively. All the prepared compounds show considerable antimicrobial activity against bacteria, yeast, and fungi.     

Preparation of leukotriene B(4) inhibitory active 2- and 3-(2-aminothiazol-4-yl)benzo[b]furan derivatives and their growth inhibitory activity on human pancreatic cancer cells

A series of 2-(2-aminothiazol-4-yl)benzo[b]furan and 3-(2-aminothiazol-4-yl)benzo[b]furan derivatives were prepared, and their leukotriene B(4) inhibitory activity and growth inhibitory activity in cancer cell lines were evaluated. Several compounds showed strong inhibition of calcium mobilization in CHO cells overexpressing human BLT(1) and BLT(2) receptors and growth inhibition to human pancreatic cancer cells MIA PaCa-2. 3-(4-Chlorophenyl)-2-[5-formyl-2-[(dimethylamino)methyleneamino]thiazol-4-yl]-5-methoxybenzo[b]furan 8b showed the most potent and selective inhibition for the human BLT(2) receptor, and its IC(50) value was smaller than that of the selected positive control compound, ZK-158252. 3-(4-Chlorophenyl)-2-[2-[(dimethylamino)methyleneamino]-5-(2-hydroxyethyliminomethyl)thiazol-4-yl]-5-methoxybenzo[b]furan 9a displayed growth inhibitory activity towards MIA PaCa-2.     

Imidazo[1,2-a]pyridines. I. Synthesis and inotropic activity of new 5-imidazo[1,2-a]pyridinyl-2(1H)-pyridinone derivatives

A series of 1,2-dihydro-5-imidazo[1,2-a]pyridinyl-2(1H)-pyridonones was synthesized and evaluated for positive inotropic activity, 1,2-Dihydro-5-imidazo[1,2-a]pyridin-6-yl-6-methyl-2- oxo-3-pyridinecarbonitrile (11a) hydrochloride monohydrate (E-1020) was found to be a potent and selective inhibitor of phosphodiesterase III and a long-acting, potent, orally active positive inotropic agent. Additional imidazo[1,2-a]pyridin-2-yl (3a), -3-yl (16), -7-yl (20) and -8-yl (24a) compounds were also prepared. Altering the pyridine substitution from the 2-position to the 6-position produced a 2-fold increase in the i.v. cardiotonic potency (ED50) from 52 to 23 micrograms/kg, while substitution at the 3-, 7- or 8-position reduced potency. In the 2-positional isomers, introduction of halogen groups enhanced the activity and 3-chloro-1,2-dihydro-5-(6-fluoroimidazo[1,2-a] pyridin-2-yl)-6-methyl-2(1H)-pyridinone (3u) was the most potent (i.v. ED50 11 micrograms/kg) in this series. E-1020 is presently under development for the treatment of congestive heart failure.     

Synthesis of some new types of 3-coumarinyl-substituted pyrazolopyrimidines and imidazothiazoles

The treatment of 3-[3-(dimethylamino)-1-oxo-2-propenyl]chromen-2-ones with 3-amino-4-cyanopyrazole gives 7-(2-oxo-2H-chromen-3-yl)pyrazolo[1,5-a]pyrimidine-3-carbonitriles. The reaction of 3-(2-bromoacetyl)coumarins with 2-amino-4-(methoxycarbonylmethyl)thiazole and 2-amino-4-methylthiazole gives methyl 2-(6-(2-oxo-2H-chromen-3-yl)imidazo[2,1-b]thiazol-3-yl)acetate and 3-(2-methylimidazo[2,1-b]thiazol-6-yl)-2H-chromen-2-ones, respectively. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 465–471, March, 2008.     

α,α-Dibromoketone precursors in the synthesis of some new thiazole derivatives: Thiazol-2-yl hydrazonobutanoates,thiazol-2-yl pyrazole-4-carboxylates and acids

In the present study, α,α-dibromoacetophenones are used as efficient precursors for the facile synthesis of several new hydrazonothiazoles, ethyl 3-((4-arylthiazol-2-yl)hydrazono)butanoates, which undergo Vilsmeier-Haack cyclization to obtain thiazolylpyrazole esters, ethyl 3-methyl-1-(4-arylthiazol-2-yl)-1H-pyrazole-4-carbxylates, basic hydrolysis of which gives the corresponding acids, 3-methyl-1-(4-arylthiazol-2-yl)-1H-pyrazole-4-carbxylic acids. All these compounds are tested for antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis; Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa and antifungal activity against Saccharomyces cerevisiae and Candida albicans.     

Synthesis of new 1,2,4-triazole[3,4-b][1,3,4]thiadiazoles bearing pyrazole as potent antimicrobial agents

A new series of 6-(aryl/heteryl)-3-(5-methyl-1-phenyl-1H-4-pyrazolyl)[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles (7a-j) has been synthesized by the reaction of 4-amino-5-(5-methyl-1-phenyl-1H-4-pyrazolyl)-4H-1,2,4-triazol-3-yl-hydrosulfide (6) with POCl(3) and the corresponding aryl/heteryl carboxylic acid, in ethanol at reflux temperature for 12 h. All the synthesized compounds were tested for in vitro activities against certain strains of bacteria such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli and fungi such as Aspergillus niger, Aspergillus nodulans, Alternaria alternate. Compounds having 4-chlorophenyl (7d), 4-aminophenyl (7f), 4-nitrophenyl (7h) and 3-pyridyl (7i) substituents at 6-position of thiadiazole ring, showed marked inhibition of bacterial and fungal growth nearly equal to the standards. The other new compounds also showed appreciable activity against the test bacteria and fungi.     

Synthesis of some new 3-[5-(2-oxo-2H-3-chromenyl)-1,3-oxazol-2-yl]-1,3-thiazolan-4-ones as antimicrobials

<正>A series of some new 2-imino-5-[(Z)-1-(4-methylphenyl)methylidene]-3-[5-(2-oxo-2H-3-chromenyl)-1,3-oxazol-2-yl]-1,3- thiazolan-4-ones 5a-j has been synthesized and assayed for their antibacterial activity against Gram-positive bacteria viz.Bacillus subtilis(ATCC 6633),Staphylococcus aureus(ATCC 6538p) and Micrococcus luteus(IFC 12708),and Gram-negative bacteria viz. Proteus vulgaris(ATCC 3851).Salmonella typhimurium(ATCC 14028) and Escherichia coli(ATCC 25922).Among the screened compounds,5d,5e,5f,5g,and 5j exhibited potent inhibitory activity compared to standard drug,and emerged as potential molecules for further development.     

A pot-economical and green synthesis of novel (benzo[d]imidazo[2,1-b]thiazol-3-yl)-2H-chromen-2-one in ethanol–PEG-600 under catalyst-free conditions

A catalyst-free, environmentally benign, and simple one-pot multi-component protocol has been developed for the efficient synthesis of novel (benzo[d]imidazo[2,1-b]thiazol-3-yl)-2H-chromen-2-one derivatives in excellent yields using ethanol-PEG-600. This novel and green protocol have the advantages of shorter reaction times, high conversions, and follow the group-assisted-purification (GAP) chemistry process, which can avoid traditional purifications, chromatography and recrystallization. This is the first report for the synthesis of benzo[d]imidazo[2,1-b]thiazol-3-yl)-2H-chromen-2-one.     

Synthesis and biological evaluation of novel 4-(6-substituted quinolin-4-yl)-N-aryl thiazol-2-amine derivatives as potential antimicrobial agents

Cyclocondensation reaction of 4-(2-bromoacetyl)quinolin-1-ium bromide ( 4a–d ) with substituted arylthiourea, ( 5a–g ) afforded 4-(6-substituted quinolin-4-yl)-N-aryl/pyridyl thiazol-2-amine ( 6a-ab ). These newly synthesized derivatives were evaluated for in vitro antibacterial activity against Escherichia coli (NCIM 2574), Proteus mirabilis (NCIM 2388) (Gram-negative strains), Bacillus subtilis (NCIM 2063), Staphylococcus albus (NCIM 2178) (Gram-positive strains) and in vitro antifungal activity against Aspergillus niger (ATCC 504) and Candida albicans (NCIM 3100). Compounds 6a , 6b , 6d , 6f , 6k , and 6l showed moderate to good antibacterial activity against S. albus. Ten derivatives 6c , 6q , 6r , 6s , 6t , 6v , 6w , 6x , 6y , and 6aa , showed moderate to good activity against A. niger. N-[4-(Quinolin-4-yl)-1,3-thiazol-2-yl]pyridin-2-amine presented comparable activity against A. niger with respect to standard drug Rouconazole.     

Synthesis and cytotoxic activity of some novel N-pyridinyl-2-(6-phenylimidazo[2,1-b]thiazol-3-yl)acetamide derivatives

A series of novel compounds bearing imidazo[2,1-b]thiazole scaffolds were designed and synthesized based on the optimization of the virtual screening hit compound N-(6-morpholinopyridin-3-yl)-2-(6-phenylimidazo[2,1-b]thiazol-3-yl)acetamide (5a), and tested for their cytotoxicity against human cancer cell lines, including HepG2 and MDA-MB-231. The results indicated that the compound 2-(6-(4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl)-N-(6-(4-(4-methoxybenzyl)piperazin-1-yl)pyridin-3-yl)acetamide (5l), with slightly higher inhibition on VEGFR2 than 5a (5.72% and 3.76% inhibitory rate at 20 μM, respectively), was a potential inhibitor against MDA-MB-231 (IC(50) = 1.4 μM) compared with sorafenib (IC(50) = 5.2 μM), and showed more selectivity against MDA-MB-231 than HepG2 cell line (IC(50) = 22.6 μM).     

Synthese von 4-[3β, 14-Dihydroxy-5β, 14β-androstan-17β-yl]-3-pyrrolin-2-on (Hothesimogenin). Partialsynthetische Versuche in der Reihe der Herzgifte, 11. Mitteilung

Synthesis of 4-[3β, 14-Dihydroxy-5β, 14β-androstan-17β-yl]-3-pyrrolin-2-one (hothesimogenin) We describe the synthesis of 4-[3β, 14-Dihydroxy-5β, 14β-androstan-17β-yl]-3-pyrrolin-2-one (24-aza-24-desoxa-digitoxigenin) (7) , starting from 3-O-acetyl-digitoxigenin (1) .     

Studies on antibacterial agents. I. Synthesis of substituted 6,7-dihydro-1-oxo-1H,5H-benzo[i,j]quinolizine-2-carboxylic acids

A series of substituted 6,7-dihydro-1-oxo-1H,5H-benzo[i,j]quinolizine-2-carboxylic acids was synthesized and tested for antibacterial activities. Among them, 9-fluoro-6,7-dihydro-5-methyl-8-(4-methyl-1-piperazinyl)-1-oxo-1H,5H- benzo[i,j]quinolizine-2-carboxylic acid (OPC-7241) exhibited potent antibacterial activity against gram-positive and -negative bacteria, including Staphylococcus aureus and Pseudomonas aeruginosa, and 9-fluoro-6,7-dihydro-8-(4-hydroxy-1-piperidyl)-5-methyl-1-oxo-1H, 5H-benzo[i,j]quinolizine-2-carboxylic acid (OPC-7251) showed potent activity characteristically against Propionibacterium acnes.     

Synthesis, structure and antifungal activity of new 3-[(5-aryl-1,3,4-oxadiazol-2-yl)methyl]benzo[d]thiazol-2(3H)-ones

A series of new 3-[(5-aryl-1,3,4-oxadiazol-2-yl)methy])benzo[d]thiazol-2(3H)-ones were synthesized by reaction of (5-substituted-2-oxobenzothiazolin-3-yl)-acetohydrazide with various aromatic acids in POCl(3) under reflux conditions. The structures of the title compounds were confirmed by 1H-NMR, 13C-NMR, IR, MS and elemental analysis. Furthermore, the structure of compound 4i was determined by single-crystal X-ray diffraction. The preliminary bioassy results indicated that some of them showed moderate inhibition activity against Colletotrichum orbiculare, Botrytis cinerea and Rhizoctonia solani.