One-pot synthesis and antibacterial activities of pyrazolo[4',3':5,6]pyrido[2,3-d]pyrimidine-dione derivatives

A one-pot and efficient method for the synthesis of pyrazolo[4',3':5,6]pyrido[2,3-d]pyrimidine-dione derivatives by condensation reaction of barbituric acids, 1H-pyrazol-5-amines and aldehydes under solvent-free conditions is reported. These products were evaluated in vitro for their antibacterial activities.     

SnCl4 · 5H2O-catalyzed synthesis of β-amino carbonyl compounds via a direct Mannich-type reaction

An efficient three-component, one-pot synthesis of β-amino carbonyl compounds from aromatic ketones, aromatic aldehydes, and aromatic amines using tin tetrachloride at room temperature in ethanol is described. The advantages of the new method are good yields (62-96%), simple workup, and inexpensive catalyst.     

InCl3 mediated one-pot multicomponent synthesis,anti-microbial,antioxidant and anticancer evaluation of 3-pyranyl indole derivatives

A simple and convenient method for the one-pot three-component synthesis of 3-pyranyl indoles has been accomplished by tandem Knoevenagel–Michael reaction of 3-cyanoacetyl indole, various aromatic aldehydes and malononitrile catalyzed by InCl₃ in ethanol under reflux conditions. The newly synthesized 3-pyranyl indoles were evaluated for anti-microbial, antioxidant, and anticancer activities. Some of the compounds showed good anticancer activity against MCF-7 breast cancer cell lines on comparison with of standard drug.     

A practical and green approach toward synthesis of 2,4,5-trisubstituted imidazoles without adding catalyst

A simple, efficient, and inexpensive procedure has been developed for the synthesis of 2,4,5-triaryl imidazoles by a three-component, one-pot condensation of benzyl, aldehydes, and ammonium acetate in refluxing ethanol without adding catalyst. The "catalyzed-by-itself" approach shows a new direction in green synthesis of the title products.     

L-proline-catalyzed enantioselective one-pot cross-Mannich reaction of aldehydes

This protocol describes a procedure for the synthesis of syn-beta-amino alpha-substituted aldehydes, versatile intermediates in synthetic organic chemistry, via asymmetric, direct, one-pot, three-component, cross-Mannich reaction of two different aldehydes. The reaction consists of two steps; one is the formation of imine by the reaction of aldehyde and p-anisidine in the presence of Pro, and the second step is the enantioselective addition reaction of enamine generated from the other aldehyde and Pro with the imine generated in the first step. As the aldehyde easily racemizes, gamma-amino alcohol was isolated and characterized after reduction. The yield and diastereo- and enantioselectivities are generally excellent. It will take approximately 26 h to complete the protocol: 0.5 h to set up the reaction, 20.5 h for the reaction and 5 h for the isolation and purification.     

Discovery of potent antiviral (HSV-1) quinazolinones and initial structure-activity relationship studies

The discovery of antiviral activity of 2,3-disubstituted quinazolinones, prepared by a one-pot, three-component condensation of isatoic anhydride with amines and aldehydes, against Herpes Simplex Virus (HSV)-1 is reported. Sequential iterative synthesis/antiviral assessment allowed structure-activity relationship (SAR) generation revealing synergistic structural features required for potent anti-HSV-1 activity. The most potent derivatives show greater efficacy than acyclovir against acute HSV-1 infections in neurons and minimal toxicity to the host.     

Study on one-pot four-component synthesis of 9-aryl-hexahydro-acridine-1,8-diones using SiO2–I as a new heterogeneous catalyst and their anticancer activity

A simple, efficient and cost-effective method for the synthesis of 9-aryl-hexahydro-acridine-1,8-diones by a one-pot four-component cyclocondensation of dimedone, aromatic aldehydes and ammonium acetate as a nitrogen source in the presence of a new heterogeneous catalyst silica iodide (SiO₂–I) in EtOH at 80 °C is described. SiO₂–I was subjected to SEM–EDX and found to have iodo group bound to the catalyst. Some of the prepared acridine-diones were found to exhibit promising anti-cancer activity against HepG2 and MCF-7 cell lines.     

One-pot, two-step enzymatic synthesis of amoxicillin by complexing with Zn2+

A one-pot, two-step enzymatic synthesis of amoxicillin from penicillin G, using penicillin acylase, is presented. Immobilized penicillin acylase from Kluyvera citrophila was selected as the biocatalyst for its good pH stability and selectivity. Hydrolysis of penicillin G and synthesis of amoxicillin from the 6-aminopenicillanic acid formed and d-p-hydroxyphenylglycine methyl ester were catalyzed in situ by a single enzyme. Zinc ions can react with amoxicillin to form complexes, and the yield of 76.5% was obtained after optimization. In the combined one-pot synthesis process, zinc sulfate was added to remove produced amoxicillin as complex for shifting the equilibrium to the product in the second step. By controlling the conditions in two separated steps, the conversion of the first and second step was 93.8% and 76.2%, respectively. With one-pot continuous procedure, a 71.5% amoxicillin yield using penicillin G was obtained.     

Asymmetric synthesis of N-protected chiral 1-aminoalkylphosphonic acids and synthesis of side chain-functionalized depsiphosphonopeptides.

Optically active 1-aminoalkylphosphonic acid derivatives were synthesized in moderate yields and optical purities via Mannich-type reactions of benzyl carbamate, aldehydes, and optically pure chlorophosphites. Side chain-functionalized depsiphosphonopeptides were also prepared in satisfactory yields directly from one-pot reactions of benzyl carbamate, aldehydes, and diethyl (R,R)-2-chloro-1,3,2-dioxaphospholane-4,5-dicarboxylate.     

Design, microwave-assisted synthesis, and spasmolytic activity of 2-(alkyloxyaryl)-1H-benzimidazole derivatives as constrained stilbene bioisosteres

A simple, fast, and efficient method for the preparation of several 2-(alkyloxyaryl)-1H-benzimidazole derivatives is reported. Compounds were synthesized through a rapid one-pot three component reaction via microwave irradiation, starting from commercially available aldehydes and o-phenylenediamine, in the presence of Na(2)S(2)O(5) and solvent-free conditions. The design of these compounds explore the hypothesis that the stilbene framework could be mimicked with an appropriate 2-(Alkyloxyphenyl)benzimidazole scaffold. This framework has a similar structural motif as the 6-phenylnaphthalene and behaves like stilbene bioisosteres. The spasmolytic activity of these compounds was recorded using isolated rat ileum test. Compound 12 was the most active of the series, showing an IC(50) of 1.19 microM.     

Direct synthesis of phosphinopeptides containing C-terminal α-aminoalkylphosphinic acids

A series of phosphinopeptides containing C-terminal α-aminoalkylphosphinic acids were prepared in good yields directly in one-pot reactions of 2-(N-benzoxycarbonylamino)alkanamides/peptide amides, aldehydes, and aryldichlorophosphines, followed by hydrolysis. In the current method, the peptide bond was formed in a Mannich-type reaction.     

Enzymatic synthesis oF L-tryptophan from D,L-2-amino-delta2-thiazoline-4-carboxylic acid and indole by Pseudomonas sp. TS1138 L-2-amino-delta2-thiazoline-4-carboxylic acid hydrolase, S-carbamyl-L-cysteine amidohydrolase, and Escherichia coli L-tryptophanase

L-Tryptophan (L-Trp) is an essential amino acid. It is widely used in medical, health and food products, so a low-cost supply is needed. There are 4 methods for L-Trp production: chemical synthesis, extraction, enzymatic synthesis, and fermentation. In this study, we produced a recombinant bacterial strain pET-tnaA of Escherichia coli which has the L-tryptophanase gene. Using the pET-tnaA E. coli and the strain TS1138 of Pseudomonas sp., a one-pot enzymatic synthesis of L-Trp was developed. Pseudomonas sp. TS1138 was added to a solution of D,L-2-amino-delta2-thiazoline-4-carboxylic acid (DL-ATC) to convert it to L-cysteine (L-Cys). After concentration, E. coli BL21 (DE 3) cells including plasmid pET-tnaA, indole, and pyridoxal 5'-phosphate were added. At the optimum conditions, the conversion rates of DL-ATC and L-Cys were 95.4% and 92.1%, respectively. After purifying using macroporous resin S8 and NKA-II, 10.32 g of L-Trp of 98.3% purity was obtained. This study established methods for one-pot enzymatic synthesis and separation of L-Trp. This method of producing L-Trp is more environmentally sound than methods using chemical synthesis, and it lays the foundations for industrial production of L-Trp from DL-ATC and indole.     

Design, synthesis, synergistic antimicrobial activity and cytotoxicity of 4-aryl substituted 3,4-dihydropyrimidinones of curcumin

3,4-Dihydropyrimidinones of curcumin were synthesized in excellent yield by multi-component one-pot condensation of curcumin, substituted aromatic aldehydes and urea/thiourea under solvent free conditions using SnCl(2)·2H(2)O catalyst. All the synthesized compounds have been characterized by IR, (1)H NMR, (13)C NMR, Mass spectra as well as elemental analyses. The synthesized compounds 4a-n were evaluated for their synergistic antimicrobial (antibacterial and antifungal) activity against bacteria and fungi. Zone of inhibition was measured by adopting disc diffusion method. In vitro minimum inhibitory concentrations were measured using broth microdilution and food poisoning method. In addition to this in vitro cytotoxicity of synthesized compounds against three human cancer lines Hep-G2, HCT-116 and QG-56 were also evaluated. Most of the compounds showed interesting antimicrobial and cytotoxic activity as compared to curcumin, that is, the compounds derived from 2-hydroxy benzaldehyde, 4-hydroxy benzaldehyde and 4-hydroxy-3-methoxy benzaldehyde showed the highest biological activity as compared to other compounds.     

Biginelli reaction catalyzed by copper nanoparticles

We recently reported a novel synthesis of copper nanoparticles from copper sulphate utilizing the charge-compensatory effect of ionic liquid [bmim]BF(4) and ethylene glycol. The nanoparticles were characterized and found to be stable for one year. Here we hypothesize that the stabilized nanoparticles should be able to catalyze one-pot multicomponent organic reactions. We show that the nanoparticles catalyzed Biginelli reaction at room temperature to give the product 3,4-dihydopyrimidinone (>90% yield in ～15 minutes) from aldehydes, β-diketoester (ethylacetoacetate) and urea (or thiourea). ). Remarkably, such high yields and rapid kinetics was found to be independent of the electronic density on the reactant aryl-aldehyde. This was probably because even the surface-active particles reacted faster in the presence of ionic liquid as compared to conventional methods. The heterocyclic dihydropyrimidinones (DHPMs) and their derivatives are widely used in natural and synthetic organic chemistry due to their wide spectrum of biological and therapeutic properties (resulting from their antibacterial, antiviral, antitumor and anti-inflammatory activities. Our method has an easy work-up procedure and the nanoparticles could be recycled with minimal loss of efficiency.     

Chlorotrimethylsilane-promoted one-pot synthesis of steroidal[17,16-d]pyrimidines

A novel and practical procedure was developed for the preparation of steroidal[17,16-d]pyrimidines by chlorotrimethylsilane (TMSCl)-promoted one-pot multicomponent Biginelli-like condensations of steroid-17-ones, urea and aromatic aldehydes. First, treatment of the steroid-17-ones with urea and aromatic aldehydes in dimethylformamide (DMF)/acetonitrile (ACN) gives the corresponding Biginelli products, following the aromatising reaction of the Biginelli products at the same time under air to yield the desired steroidal[17,16-d]pyrimidines (78-88%). Since steroidal[17,16-d]pyrimidines with hydroxyl group can be subsequently converted into steroidal[17,16-d]pyrimidine derivatives, this general method provides a highly efficient route to these biologically important compounds.     

An improved microwave assisted one-pot synthesis, and biological investigations of some novel aryldiazenyl chromeno fused pyrrolidines

An improved microwave assisted one-pot method for the synthesis of twelve new aryldiazenylchromeno [4,3-b] pyrrolidines via intramolecular azomethine ylide cycloaddition route is described. The method is efficient and advantageous over conventional and solvent-free thermal methods. The stereochemistry of the compounds was confirmed on the basis of various NMR experiments, and finally by single crystal X-ray diffraction data. N-Methyl or ethyl pyrrolidine based heterocycles gave good biological activities.     

Express Protocol for Functionalization of Polymer Supports for Oligonucleotide Synthesis

Abstract

A rapid and general one-pot method is described for the attachment of the leader nucleoside onto the polymer supports, suitable for polymer supported oligonucleotide synthesis following oxidation-reduction condensation. The method can also be used for support functionalisation in fully automated DNA synthesizer prior to oligonucleotide synthesis.     

An efficient, simple and expedition synthesis of 1-amidoalkyl-2-naphthols as 'drug like' molecules for biological screening

An efficient and direct protocol for the preparation of amidoalkyl naphthols employing a multi-component, one-pot condensation reaction of beta-naphthol, aromatic aldehydes and acetamide in the presence of ferric hydrogensulfate under solvent, solvent-free and microwave conditions is described. The thermal solvent-free and microwave green procedures offer advantages such as shorter reaction times, simple work-up, excellent yield, recovery and reusability of catalyst. It is noteworthy that 1-amidomethyl-2-naphthols can be converted into important biological 'drug like' active 1-aminomethyl-2-naphthols derivatives by amide hydrolysis.     

Preparation of 1-C-glycosyl aldehydes by reductive hydrolysis

Reductive hydrolysis of various protected glycosyl cyanides was carried out using DIBAL-H to form aldimine alane intermediates which were then hydrolyzed under mildly acidic condition to provide the corresponding aldehyde derivatives. While 1-C-formyl glycal and 2-deoxy glycosyl derivatives were stable during isolation and storage 1-C-glycosyl formaldehydes in the gluco, galacto and manno series were sensitive and decomposition occurred by 2-alkyloxy elimination. A one-pot method using N,N′-diphenylethylenediamine to trap these aldehydes in stable form was developed. Reductive hydrolysis of glycosyl cyanides offers valuable aldehyde building blocks in a convenient way which can be applied in the synthesis of complex C-glycosides.     

A Novel Oxazolidine Linker for the Synthesis of Peptide Aldehydes

A reliable method for solid-phase synthesis of peptide aldehydes by using a new oxazolidine linker is described. Based on a comparative study using the usual cleavage protocol as is used for the Fmoc-based peptide synthesis, we found that this new linker is more appropriate for the synthesis of peptide aldehydes compared with the precedent acetal, semicarbazone or threonine linker. Whereas N-Acylated oxazolidines might be partially deprotected to non-N-acylated intermediates in the TFA cocktail containing several soft nucleophiles which cause significant side reactions, the new oxazolidine linker could produce the desired peptide aldehydes by simple Et₂O washing and subsequent aqueous workup in high chemical yields and purity. We demonstrate the new method is useful especially for the preparation of highly functionalized long-chain peptide aldehydes which require several scavenger chemicals in the final deprotection step. This paper is dedicated to the memory of the late Prof. R. Bruce Merrifield, who passed away May 14, 2006.