One-pot multicomponent synthesis of novel thiazol-2-imines via microwave irradiation and their antifungal evaluation

Microwave-assisted green approach is developed for an efficient synthesis of thiazol-2-imines under catalyst-free conditions. The desired products are formed by one-pot three-component reaction which is an improvised method for Hantzsch thiazole synthesis. The microwave-assisted protocol gives excellent yields with high purity in just 10–15?min. All the synthesized compounds have been screened for antifungal activity and some of the derivatives show a broad spectrum against fungal pathogens.     

One-pot multicomponent synthesis of novel 3, 4-dihydro-3-methyl-2(1H)-quinazolinone derivatives and their biological evaluation as potential antioxidants,enzyme inhibitors,antimicrobials, cytotoxic and anti-inflammatory agents

A series of novel 3, 4-dihydro-3-methyl-2(1H)-quinazolinone derivatives with substituted amine moieties (1–13) and substituted aldehyde (S) were designed and synthesized by a reflux condensation reaction in the presence of an acid catalyst to get N-Mannich bases. Mannich bases were evaluated pharmacologically for their antioxidant, α-amylase enzyme inhibition, antimicrobial, cell cytotoxicity and anti-inflammatory activities. Most of the compounds exhibited potent activities against these bioassays. Among them, SH1 and SH13 showed potent antioxidant activity against DPPH free radical at IC₅₀ of 9.94 ± 0.16 µg/mL and 11.68 ± 0.32 µg/mL, respectively. SH7, SH10 and SH13 showed significant results in TAC and TRP antioxidant assays, comparable to that of ascorbic acid. SH2 and SH3 showed potent activity in inhibiting α-amylase enzyme at IC₅₀ of 10.17 ± 0.23 µg/mL and 9.48 ± 0.17 µg/mL, respectively, when compared with acarbose (13.52 ± 0.19 µg/mL). SH7 was the most active against gram-positive and gram-negative bacterial strains, SH13 being the most potent against P. aeruginosa by inhibiting its growth up to 80% (MIC = 11.11 µg/mL). SH4, SH5 and SH6 exhibited significant activity against some fungal strains. Among the thirteen synthesized compounds (SH1-SH13), four were screened out based on the results of brine shrimp lethality assay (LD₅₀) and cell cytotoxicity assay (IC₅₀), to determine their anti-cancer potential against Hep-G2 cells. The study was conducted for 24, 48, and 72 h. SH12 showed potent results at IC₅₀ of 6.48 µM at 72 h when compared with cisplatin (2.56 µM). An in vitro nitric oxide (NO) assay was performed to shortlist compounds for in vivo anti-inflammatory assay. Among shortlisted compounds, SH13 exhibited potent anti-inflammatory activity by decreasing the paw thickness to the maximum compared to the standard, acetylsalicylic acid (ASA).     

One-pot multicomponent synthesis and antimicrobial evaluation of novel tricyclic indenopyrimidine-2-amines

The synthesis of novel tricyclic indenopyrimidine-2-amines from 3,3-dimethyl-/3-methyl-2H-indanones has achieved by base-catalyzed one-pot three-component reaction. The desired products are formed within 10 hours after addition at reflux temperature. This multicomponent approach offers a viable protocol for the construction of indenopyrimidine-2-amines in single-step without the isolation of the intermediates 3,3-dimethyl/3-methyl-2-(4-substituted benzylidene)-2,3-dihydro-1H-inden-1-ones. All the synthesized compounds have been screened for antimicrobial activity and some of the derivatives show comparable activity against bacterial and fungal isolates.     

One-pot multicomponent synthesis of functionalized 2,5-disubstituted-1,3,4-thiadiazine derivatives

An atom-efficient and environmentally friendly approach to the synthesis of 2,5-disubstituted-1,3,4-thidiazine derivatives has been developed. These compounds were synthesized by a reaction of 2-(2-bromoacetyl)benzofuran and thiocarbohydrazide with various aryl aldehydes, acetylacetones, and pthalic anhydrides in good yields. The advantages of this methodology are mild reaction conditions, easy workup procedure, clean reaction profile, shorter reaction time, and a wide range of substrate applicability. The structures of all synthesized compounds were confirmed from their analytical and spectral data.     

Microwave-assisted synthesis of 5-aryl-3-hydroxy-2-oxindole derivatives and evaluation of their antiglaucomic activity

A set of new 5-aryl-3-hydroxy-2-oxindoles was synthesized by decarboxylative condensation of the corresponding 5-aryl-substituted isatins with malonic or cyanoacetic acids under microwave irradiation. The antiglaucomic activity of the obtained compounds was evaluated. The most water soluble compounds can reduce the intraocular pressure (IOP) up to 2 Torr.     

Green synthesis of novel quinoline based imidazole derivatives and evaluation of their antimicrobial activity

We have described the conventional and microwave method for the synthesis of N-(4-((2-chloroquinolin-3-yl)methylene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)(aryl)amides 3a–l. It is observed that the solvent-free microwave thermolysis is a convenient, rapid, high-yielding, and environmental friendly protocol for the synthesis of quinoline based imidazole derivatives when compared with conventional reaction in a solution phase. Antimicrobial activity of the newly synthesized compounds is screened in vitro on the following microbial cultures: Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 1688), Staphylococcus aureus (MTCC 96), Streptococcus pyogenes (MTCC 442), Candida albicans (MTCC 227), Aspergillus niger (MTCC 282), Aspergillus clavatus (MTCC 1323). All the synthesized bio-active molecules are tested for their in vitro antimicrobial activity by bioassay namely serial broth dilution. Among these compounds 3c, 3d, 3f, 3h and 3j show significant potency against different microbial strains. All the compounds have been characterized by IR, ¹H NMR, ¹³C NMR and mass spectral data. On the basis of statistical analysis, it is observed that these compounds give significant co-relation.     

Synthesis of novel 3-deoxy-3-C-triazolylmethyl-allose derivatives and evaluation of their biological activity

Recently, monosaccharide-triazole conjugates have proved to possess a large variety of useful biological activities. This paper describes synthesis of a new series of 3-deoxy-3-C-triazolylmethyl-allose derivatives. These new compounds are obtained from acetonide-protected 3-deoxy-3-azidomethyl allose and commercial alkynes via Cu(I) catalyzed 1,3-dipolar cycloaddition. The obtained molecular scaffolds differ from those described earlier by the presence of a methylene linker (-CH₂-) between the C(3) of allose and the triazole moiety. It was demonstrated that acetonide-protected monosaccharide, 3-deoxy-3-C-(4-phenyl-1H-1,2,3-triazol-1-yl)methyl-1,2:5,6-di-O-isopropylidene-α-d-allofuranose, inhibited α-L-fucosidase for 26% at 0.1 mM concentration, but a deprotected analog, 3-deoxy-3-C-(4-(4-tert-butylphenyl)-1H-1,2,3-triazol-1-yl)methyl-β-d-allofuranose, showed 15% inhibition of β-glucosidase at 1 mM concentration.      

One-pot multicomponent diastereoselective synthesis of novel dihydro-1H-furo[2,3-c]pyrazoles

An efficient method was developed for the diastereoselective synthesis of novel fused dihydro-1H-furo[2,3-c]pyrazole by a one-pot, four-component reaction of β-keto ester, hydrazine, aromatic aldehyde, and pyridinium ylide in the presence of triethylamine under microwave irradiation in solvent-free conditions in good yields. The merits of this cascade Knoevenagel condensation/Michael addition/cyclization sequence include its high atom economy, good yields, and efficiency of producing three new bonds (two C–C and one C–O) and two stereocenters in a single operation.     

One-pot chemoselective synthesis of novel fused pyrimidine derivatives

One-pot triple-component reaction of 4-hydroxycoumarin with aromatic aldehydes and 2-aminobenzimidazole, 3-amino-1H-1,2,4-triazole, or 6-aminouracil in acetonitrile in the presence of catalytic amounts of sulfamic acid led to a chemoselective synthesis of chromeno[4,3-d]pyrimidine-6-one, triazolo[1,5-a]pyrimidin-5-one, and pyrido[2,3-d]-pyrimidine-2,4,7-trione derivatives, respectively, in good yields.     

One-pot synthesis of novel 1,2,3-triazole-pyrimido[4,5-c]isoquinoline hybrids and evaluation of their antioxidant activity

A series of novel pyrimido[4,5-c]isoquinolines (3a–3h) and 1,2,3-triazole-coupled pyrimido[4,5-c]isoquinolines (4a–4h) were synthesized in good to excellent yields in the one-pot method. The reaction of 6-amino-1,3-dimethyluracil with different 2-iodo benzoyl chlorides using Pd catalyst in dimethylformamide afforded corresponding pyrimido[4,5-c]isoquinolines (3a–3h). One-pot reaction of pyrimido[4,5-c]isoquinolines with propargyl bromide and benzyl azide in THF at room temperature furnished 1,2,3-triazole-coupled pyrimido[4,5-c]isoquinoline (4a–4h). In vitro antioxidant activity examination revealed that compounds 4d and 4c found to exhibit potent antioxidant activity as compared to the standard drug Trolox with IC₅₀ values 6.02?±?0.6 and 12.18?±?0.9?µM, respectively.     

One-pot multicomponent synthesis of some 5,6-dihydro-benzo[h]quinoline derivatives

5,6-Dihydrobenzo[h]quinoline derivatives 4a–f and 5a–c were prepared via condensation of the corresponding arylidenes 2, with 1-tetralone in the presence of ammonium acetate and sodium methoxide, respectively, following thermal, microwave and ultrasound methodologies. The yields of 4a–f were moderate when the latter two methodologies used, but the products were pure. Ultrasound and microwave irradiation methods were also used in the synthesis of 4-aryl-3-cyano-1,2,5,6-tetrahydro-benzo[h]quinoline-2-ones (6a–e) and its analogues 7a,b. The majority of compounds 4–7 were synthesized via one-pot multicomponent reactions of aldehydes, active cyanomethylene compounds, 1-tetralone and ammonium acetate. Attempts to cyclocondensation of the aminocyano derivative 4a,d with acetic anhydride in presence of conc. H₂SO₄ failed; instead the acetylamino derivative 8 was isolated. On the other hand, refluxing of 4d with formamide in DMF led to the formation of dihydrobenzo-pyrimidoquinoline 9 giving good yield. All prepared condensates were structurally elucidated by various spectroscopic methods. Screening of the potential cytotoxicity for compounds 4a–f on five cell lines, namely: colorectal carcinoma (HCT-116), Hepatocellular carcinoma (HEPG2), Human breast adenocarcinoma (MCF7), Cervix adenocarcinoma (HELA) and Glioblastoma (U251), did not show any cytotoxic activity.     

One-pot multicomponent synthesis of polysubstituted indolizines

Concise and efficient four-component tandem approaches to polysubstituted indolizines have been developed under metal-free and mild aerobic conditions in refluxing acetonitrile. The mechanism of the novel reactions was proposed involving the formation of pyridinium ylides and α,β-unsaturated ketones with subsequent 1,3-dipolar cycloaddition and aromatization reaction.     

One-pot multistep synthesis of 3-aminoindolizine derivatives

We have developed an efficient one-pot multistep sequence to the synthesis of 3-aminoindolizine derivatives by using Hantzsch ester (9) as a mild hydride transfer agent. The reaction scope was investigated and the effect of substrates on reaction outcomes was discussed.     

One-pot synthesis of cotarnine 1-alkynyl derivatives

Russian Chemical Bulletin - Cotarnine chloride reacts with terminal acetylenes with short-time heating in acetonitrile in the presence of the catalytic system CuI—morpholine to form cotarnine...     

Design and synthesis of novel cytotoxic podophyllotoxin derivatives

<正>In order to investigate the effect of different C4 linkage moieties on the cytotoxicity of podophyllotoxin derivatives,novel 4-Nand 4-C-substituted 4'-O-demethylepipodophyllotoxin derivatives were designed and synthesized.All the compounds were tested against A549 and MCF-7 tumor cells in vitro,and six compounds showed significant cytotoxicity.The most active compound 9f was superior to GL-331,and exhibited potent cytotoxicity with IC_(50) value at 10~(-7) mol/L level.     

One-pot,three-component synthesis and in vitro antibacterial evaluation of novel 3-amino-N-benzyl-1-aryl-1H-benzo[f]chromene-2-carboxamide derivatives

A series of novel 3-amino-N-benzyl-1-aryl-1H-benzo[f]chromene-2-carboxamides have been synthesized by the reaction of N-benzyl-2-cyanoacetamide with 2-naphthol and aromatic aldehydes in the presence of piperidine as a base. The chemical structures of all the compounds were confirmed by spectroscopic methods as well as elemental analysis. In addition, the antibacterial activities of some target compounds against Gram-negative and Gram-positive bacteria in vitro were determined. Among these compounds, 4b, 4c, 4h and 4i exhibited antibacterial effects. The advantages of the present work reaction are clean reaction, metal-free transition, environmentally friendly approach to prepare different benzo[f]chromene-2-carboxamide derivatives, good yields, low cost, readily available starting materials and in addition does not need cumbersome procedure.     

One-pot synthesis of 5-amino 4-cyano pyrrole derivatives

One-pot synthesis of 5-amino 4-cyano pyrrole derivatives is herein disclosed. The described method consists of four steps and gives new pyrrole derivatives in moderate to good yields. This synthesis can be used for a large scale preparation.     

One-pot multicomponent synthesis of indol-3-yl-hydrazinyl thiazoles as antimicrobial agents

A series of novel mono- and bis(indol-3-yl)hydrazinyl thiazole derivatives were efficiently synthesized via one-pot cyclocondensation of mono- or bis(indole-3-carbaldehyde), thiosemicarbazide, and phenacyl bromides. The structure of the products was confirmed by Fourier-transform infrared (FT-IR), ¹H nuclear magnetic resonance (NMR), and ¹³C NMR spectra. All synthesized compounds were evaluated for in vitro antibacterial activity against Gram-positive (Bacillus subtilis and Micrococcus luteus) and Gram-negative bacteria (Pseudomonas aeruginosa and Salmonella enteritis). Among the compounds screened, a few were found to be highly effective antibacterial agents. The bis-compounds with OCH₃ donating group exhibited good activity against the Gram-positive bacteria.