An ionic liquid mediated one-pot synthesis of substituted thiazolidinones and benzimidazoles

An expeditious one-pot synthesis of 2,3-diaryl/2-aryl-3-heteroaryl-1,3-thiazolidin-4-ones and 1-aryl-1H,3H-thiazolo[3,4-a]benzimidazoles have been accomplished by condensing hetero/aromatic amine, 2-mercaptoacetic acid, aromatic aldehyde and 1,2-phenylenediamine, 2-mercaptoacetic acid and aromatic aldehyde, respectively, in ionic liquids, viz, 1-butyl-3-methyl-imidazolium tetrafluoroborate and 1-methoxyethyl-3-methylimidazolium trifluoroacetate.     

Electrochemically synthesized polymer of the plant substance embelin (2,5-dihydroxy-3-undecyl-1,4-benzoquinone)

Among the possible new materials for microelectronics, quinones have a number of significant advantages. Similarly, polymers with quinone functionality possess biodegradability. Because natural polymers are promising candidates for functional materials for the future, we have initiated studies on the polymers of natural products. In the present study, a natural quinone (a plant substance) extracted from Embelier libes distributed in the Kerala state of India was electrochemically polymerized and its properties were investigated. The redox activity, electrical conductivity, and biodegradability are discussed.     

Tin mediated Barbier type allylation in ionic liquids

The Barbier type allylation of carbonyl compounds is a useful organic transformation as the resultant homoallylic alcohols are important building blocks for many biologically active molecules. Tin mediated Barbier allylation of different carbonyl compounds in room temperature ionic liquid, [BMIM][BF₄] afforded the corresponding homoallylic alcohols in good to excellent yields. The ionic liquid was successfully recycled and reused in allylation reactions.     

Bioprocess Optimization of Furanocoumarin Elicitation by Medium Renewal and Re-elicitation: A Perfusion-Based Approach

Effect of various abiotic (methyl jasmonate, salicylic acid) and biotic (yeast extract, Aspergillus niger) elicitors on furanocoumarin production and in situ product removal was studied using shoot cultures of Ruta graveolens L. Elicitation by yeast extract (1% w/v) on day 15 was most effective. It led to 7.8-fold higher furanocoumarin production that was attained 24 h after elicitation and 43% of the product was released into the medium. Changes in the relative concentration of furanocoumarins produced depend on the elicitor used. Molar ratio of bergapten increased to 93% in response to yeast extract. With the perspective of developing a commercially feasible process, an approach for preserving viability of biomass and its reuse needs to be developed. For this, medium renewal strategy was investigated. Removal of the spent medium 48 h after elicitation allowed in situ product removal and proved effective in revival of cultures, allowing reuse of biomass. A week after medium renewal, the revived biomass was re-elicited and a second furanocoumarin production peak was obtained. A perfusion-based bioprocess optimization approach, employing elicitation coupled with medium renewal with subsequent re-elicitation, as a new strategy for improved furanocoumarin production, has been suggested.     

One‐Pot,Three‐Component Synthesis of Novel Spiro[3H‐indole‐3,2′‐thiazolidine]‐2,4′(1H)‐diones in an Ionic Liquid as a Reusable Reaction Media

A facile one‐pot, three‐component protocol for the synthesis of novel spiro[3H‐indole‐3,2′‐thiazolidine]‐2,4′(1H)‐diones by condensing 1H‐indole‐2,3‐diones, 4H‐1,2,4‐triazol‐4‐amine and 2‐sulfanylpropanoic acid in [bmim]PF₆ (1‐butyl‐3‐methyl‐1H‐imidazolium hexafluorophosphate) as a recyclable ionic‐liquid solvent gave good to excellent yields in the absence of any catalyst (Scheme 1 and Table 2). The advantages of this protocol over conventional methods are the mild reaction conditions, the high product yields, a shorter reaction time, as well as the eco‐friendly conditions.     

Chiral pool based synthesis of pyrrolidinium ionic liquids

Chiral ionic liquids show promising applications in various different fields. A series of pyrrolidinium-based chiral ionic liquids bearing a chiral cation, a chiral anion or both was prepared in good yields using an efficient, economic and simple pathway. The chirality was introduced using (l)-lactate and (l)-menthol derivatives. The resultant chiral compounds were characterized by both spectroscopy and polarimetry. We envision that these new chiral compounds can serve as effective reaction media and chiral catalysts for asymmetric reactions, which are presently being investigated in our lab.     

Investigation of the reactions of fluorinated isatins and N-acetylisatins with thiocarbohydrazide: Synthesis of a novel spiro system: 2-oxo-1′,2′,4′,5′-tetrahydrospiro[3H-indole-3,3′-1,2,4,5-tetrazine]-6′-thione

A novel system 2-oxo-1′,2′,4′,5′-tetrahydrospiro[3H-indole-3,3′-1,2,4,5-tetrazine]-6′-thione has been synthesized by the treatment of fluorinated isatins with thiocarbohydrazide in aqueous ethanolic medium. Under exactly similar conditions, N-acetylisatin gave exclusively thiocarbohydrazone. The spiro product, on treatment with acetic acid, gave fluorinated isoindigo. Characterization of these products have been done by elemental analyses, ir, pmr and mass spectral studies.     

Studies in spiroheterocycles. Part V. Synthesis of new fluorinated spiro[3H-indole-3,2′-oxiran]-2(1H)-ones

Reinvestigation of the reaction of 3-aroylmethyleneindol-2-ones with hydrogen peroxide has revealed that a 1:1 isomeric mixture of spiro[3H-indole-3,2′-oxiran]-2(1H)-ones is formed. The structures of the two isomers have been confirmed by their ir, pmr and mass spectral studies. Mass fragmentation patterns of these compounds are discussed.     

Physicochemical Investigation of Engineered Nanosuspensions Containing Model Drug,Lansoprazole

Lansoprazole is a proton-pump inhibitor used in treatment of gastric ulcers, gastroesophageal reflux disease (GERD), and Zollinger–Ellison syndrome. The objective of the study was physicochemical investigation and comparative characterization of nanosuspensions of lansoprazole by complexing with β-cyclodextrin and β-cyclodextrin-based nanosponges to enhance its solubility and stability. Inclusion complexes of lansoprazole with β-cyclodextrin and nanosponges were prepared by physical method and polymer condensation method, respectively. Particle size, zeta potential, encapsulation efficiency, in vitro release, FTIR, and Differential Scanning Calorimeter (DSC) studies were used as characterization parameters. The average particle size of lansoprazole nanoparticles was found to be in the range of 178.7 ± 6.39 nm to 204.9 ± 2.91 nm. The high zeta potential values were attained to ensure a high-energy barrier and favor a good stability of nanosuspensions. In vitro release study showed the controlled release of lansoprazole, which was more satisfactory than individual drug. FTIR spectroscopy showed that there was interaction of cyclodextrin and its nanosponges with drug. DSC study revealed that drug was involved in complexion with cyclodextrin and nanosponges. Solubility and stability of lansoprazole were remarkably improved by inclusion complexation. Based on these findings, it can be concluded that engineered nanosuspension of lansoprazole is a promising carrier for nanoparticulate drug delivery in gastric ulcer.     

Amino acid analysis by using comprehensive two-dimensional gas chromatography

The separation characteristics of alkylchloroformate-derivatised amino acids (AAs) by using comprehensive two-dimensional gas chromatography (GC×GC) is reported. The use of a low-polarity/polar column set did not provide as good a separation performance as that achieved with a polar/non-polar column set, where the latter appeared to provide less correlation over the separation space. The degree of component correlation in each column set was estimated by using the correlation coefficient (r²; for ¹t_R and ²t_R data) with the low-polarity/polar and polar/low-polarity sets returning correlation coefficients of 0.86, and 0.00 respectively, under the respective conditions employed for the experiments. The 1.5-m non-polar ²D column (0.1-mm ID; 0.1-m film thickness) gave peak halfwidths of the order of 50–80 ms. Linearity of detection was good, over a three order of magnitude concentration range, with typical lower detection limit of ca. 0.01 mg L^–1, compared with 0.5 mg L^–1 for normal GC operation with splitless injection. The method was demonstrated for analysis of AAs in a range of food and beverage products, including wine, beer and honey. The major AA in these samples was proline. The Heineken beer sample had a relatively more complex and more abundant AA content compared with the other beer sample. The wine and honey samples also gave a range of AA compounds. Repetition of the sample preparation/analysis procedure for the honey sample gave acceptable reproducibility for individual AAs.