Three multicomponent reactions of 3,5-dimethyl-4-nitroisoxazole

The title compound is used to prepare 3-arylglutaric acids, bis-isoxazoles and bis-pyrazoles from commercially available materials. The methodologies described have afforded important synthetic intermediates in high yields and without the use of chromatography.     

2,7-diphenyl[1]benzoselenopheno[3,2-b][1]benzoselenophene as a stable organic semiconductor for a high-performance field-effect transistor

[1]Benzoselenopheno[3,2-b][1]benzoselenophene (BSBS) and its 2,7-diphenyl derivative (DPh-BSBS) were readily synthesized from diphenylacetylene and bis(biphenyl-4-yl)acetylene, respectively, with a newly developed straightforward selenocyclization protocol. In contrast to the parent BSBS that has poor film-forming properties, the diphenyl derivative DPh-BSBS formed a good thin film on the Si/SiO(2) substrate by vapor deposition. X-ray diffraction examination revealed that this film consists of highly ordered molecules that are nearly perpendicular to the substrate, making it suitable for use in the fabrication of organic field-effect transistors (OFETs). When fabricated at different substrate temperatures (room temperature, 60 degrees C, and 100 degrees C) in a "top-contact" configuration, all the DPh-BSBS-based OFET devices exhibited excellent p-channel field-effect properties with hole mobilities >0.1 cm(2) V(-1) s(-1) and current on/off ratios of approximately 10(6). This high performance was essentially maintained over 3000 continuous scans between V(g) = +20 and -100 V and reproduced even after storage under ambient laboratory conditions for at least one year.     

Electron transfer reactions. Reactions of epoxyketones and benzoylaziridines with potassium

The results of our studies on the reaction of some epoxyketones and aziridines with potassium in tetrahydrofuran (THF) are presented. Treatment of trans-l,3-diphenyl-2,3-epozypropan-1-one (1a.) with, potassium, for example, gives a mixture of acetophenone (9), the chalcone 4a, the dihydrochalcone 14a, the cyclopentene isomers 20a and 21a, the hydroxy acid 10a and benzoic acid 6, whereas the reaction of 1a with potassium, under oxygen saturation, gives a mixture of 4a, 14a, 6, the diketone 17a, the dihydroxycarboxylic acid 7a and the hydroxyfuranone 19a. The reaction of 1a. with potassium superoxide, however gives a mixture of 6, 7a and 19a. Similar results are obtained in the reaction of trans-2,3-epoxy-1-phenyl-3-p-tolylpropan-1-one 1b with potassuum. The reaction of 7-oxa-2,3-dibenzoylbtcyclo[2 2 1]hepta-2,5-diene (22a) with potassium gives a mixture of 6 and o-dibenzoylbenzene (26a), whereas 2,3-dibenzoyl-1,4-dihydro-1,4-diphenyl-1,4-epoxynaphthalene (22b), under analogous conditions, gives a mixture of 6, 1,3-diphenylisobenzofuran (25b), 26a, 2,3-dibenzoyl-1,4-diphenylnapntnelene (26b) and 2-benzoyl-1,4-dtphenylnaphthalene (27b). Treatment of the benzoylaztridines 28a-d with potassium gives the stilbenes, 33a,c, the hydroxy amides, 34,a,c,d, and carboxylic acids 6, 11b, whereas the aziridine 35, on treatment with potassium, gives a mixture of the isoquinoline 37 and the phthalimidine 39. Cyclic voltammetric and pulse radiolysis studies have been carried out, in an attempt to characterize the radical anion intermediates involved in these reactions. Document No. NDRL-3120 from the Notre Dame Radiation Laboratory and No. RRLT-PRU-5 from the Regional Research Laboratory Trivandrum.     

Synthesis of star-shaped pyrrole-based C3-symmetric molecules via ring-closing metathesis,Buchwald–Hartwig cross-coupling and Clauson–Kaas pyrrole synthesis as key steps

We have demonstrated three contrasting synthetic strategies to assemble pyrrole-based C₃-symmetric molecule. Here, ring-closing metathesis (RCM), Buchwald–Hartwig cross-coupling and Clauson–Kaas pyrrole synthesis have been used as key steps. Interestingly, readily available starting materials such as 4-aminoacetophenone, 4-bromo acetophenone and 4-nitro acetophenone have been used as starting materials. Grubbs’ first generation catalyst (G-I) is useful for one-pot RCM and aromatization sequence without the involvement of additional reagents. We also report photophysical properties of these star-shaped molecules.     

Enantioselective anti-Mannich reaction catalyzed by modularly designed organocatalysts

A highly stereoselective method for achieving the anti-Mannich reaction of aldehydes and ketones with ethyl (4-methoxyphenylimino)acetate was realized using the modularly designed organocatalysts (MDOs) self-assembled from cinchona alkaloid derivatives and (R)-pyrrolidien-3-carboxylic acid in the reaction media. The desired anti-Mannich products were obtained in good to excellent yields (up to 93%), excellent diastereoselectivities (up to 99:1 dr), and good to high enantioselectivities (up to 99% ee).     

Phenacylsulfonylacetic esters — source for thiadiazoles,triazoles and oxadiazoles

A new class of thiadiazoles, triazoles and oxadiazoles were prepared from phenacylsulfonylacetic ester by protecting the carbonyl group by oximation. Deoximation was affected by using β‐cyclodextrin in the presence of an oxidizing agent.     

A three-dimensional chemical phase pharmacophore mapping,QSAR modelling and electronic feature analysis of benzofuran salicylic acid derivatives as LYP inhibitors

Lymphoid tyrosine phosphatase (LYP), encoded by the PTPN22 gene, has a critical negative regulatory role in T-cell antigen receptor (TCR) and emerged as a promising drug target for human autoimmune diseases. A five-point pharmacophore with two hydrogen bond acceptors, one hydrogen bond donor and two aromatic ring features was generated for a series of benzofuran salicylic acid derivatives as LYP inhibitors in order to elucidate their anti-autoimmune activity. The generated pharmacophore yielded a significant 3D-QSAR model with r² of 0.9146 for a training set of 27 compounds. The model also showed excellent predictive power with Q² of 0.7068 for a test set of eight compounds. The investigation of the 3D-QSAR model has revealed the structural insights which could lead to more potent analogues. The most active and inactive compounds were further subjected to electronic structure analysis using density functional theory (DFT) at B3LYP/3?21^?G level to support the 3D-QSAR predictions. The results obtained from this study are expected to be useful in the proficient design and development of benzofuran salicylic acid derivatives as inhibitors of LYP.     

Development of liquid chromatography-triple quadrupole mass spectrometric method for the quantitative determination of a novel adjuvant,Imidazoquinoline gallamide in aluminum hydroxide gel-Imidazoquinoline gallamide and COVAXIN

Imidazoquinoline gallamide is a toll-like receptor 7/8 agonist, belongs to the imidazoquinoline class, has the potential to activate antigen-presenting cells, and enhances immune response, primarily Th1 response. The COVAXIN is a whole virion inactivated Coronavirus disease 2019 vaccine formulated with this novel adjuvant called, aluminum hydroxide gel Imidazoquinoline gallamide, wherein, Imidazoquinoline gallamide is chemisorbed onto aluminum hydroxide gel. Herein, an analytical method based on liquid chromatography-tandem mass spectrometry was developed to identify and quantify Imidazoquinoline gallamide in aluminum hydroxide gel Imidazoquinoline gallamide and COVAXIN. The multiple reaction monitoring transitions were optimized for Imidazoquinoline gallamide quantification are [M+H]⁺ ions with 512.24→343.19 m/z (quantifier ion) and 512.24→360.22 m/z (qualifier ion). The developed method was validated as per the international conference on harmonization quality2 revison1 guidelines. The method was linear in the range of 0.025–10 µg/mL with a coefficient of determination of 0.9985 and the limit of quantification is 0.025 µg/mL. The accuracy was in the range of 82–121 % and intra- and inter-day precision was less than 7.1% and 5.39%, respectively. The expanded uncertainty results are 9.2% for Imidazoquinoline gallamide in the sample. The validated method was successfully applied to evaluate Imidazoquinoline gallamide concentration in every batch of COVAXIN.