D. Muralidharan

A novel application of the oxidizing properties of urea nitrate and peroxydisulfate-cobalt(II): aromatization of NAD(P)H model Hantzsch 1,4-dihydropyridines

4-Alkyl or aryl substituted derivatives of Hantzsch 1,4-dihydropyridine were readily oxidized by urea nitrate under microwave irradiation or refluxing conditions to the corresponding pyridine derivatives in quantitative yields. The oxidation reaction was also effected by peroxydisulfate in the presence of cobalt(II) in aqueous acetonitrile under refluxing conditions. When n-propyl, n-butyl and cinnamyl were the substituent groups in the 4-position, a mixture of 4-substituted and unsubstituted pyridines were formed. The catalysts used in the reaction are inexpensive and provide high yields in short reaction times.

Synthesis, antimicrobial and antioxidant evaluation of quinolines and bis(indolyl)methanes

An improved and practical synthesis of substituted quinolines and bis(indolyl)methanes was achieved under microwave condition using Zn(OTf)(2) as catalyst. The synthesized compounds have been screened for antimicrobial and antioxidant activities.

Triphenylphosphonium perchlorate as an efficient catalyst for mono- and bis-intramolecular imino Diels-Alder reactions: synthesis of tetrahydrochromanoquinolines

Triphenylphosphonium perchlorate (TPP) is found to be an efficient catalyst for the mono- and bis-intramolecular imino Diels–Alder (IMIDA) reaction of aldimines derived from aromatic amines and O-allyl derivatives of salicylaldehydes to afford the corresponding tetrahydrochromano[4,3-b]quinolines in excellent yields and short reaction times under mild conditions.

Regioselective synthesis and biological evaluation of bis(indolyl)methane derivatized 1,4-disubstituted 1,2,3-bistriazoles as anti-infective agents.

The regioselective synthesis of 1,4-disubstituted 1,2,3-bistriazoles from a variety of N-propargyl bis(indolyl)methanes with sodium azide using CuI as the catalyst in polyethyleneglycol-400 is reported. This process is of considerable synthetic advantages in terms of high atom economy, low environmental impact, mild reaction condition and good yields. The synthesized compounds have also been screened for their biological activity.

SYNTHESIS OF HANTZSCH 1,4-DIHYDROPYRIDINES UNDER MICROWAVE IRRADIATION

ABSTRACT Biologically active substituted 1,4-dihydropyridines have been synthesized in excellent yields by the reaction of aldehydes, ethyl or methyl acetoacetic ester and ammonium acetate under microwave irradiation (MWI) within 0.75–3 min.

Microwave-assisted one-pot synthesis of benzothiazole and benzoxazole libraries as analgesic agents

AbstractMicrowave-assisted synthesis of benzothiazole and benzoxazole libraries via PIFA promoted cyclocondensation of 2-aminothiophenols/2-aminophenols with aldehydes under one-pot condition in good to excellent yields was achieved. Twenty compounds have been investigated for their analgesic activity and showed moderate to good activity. Graphical AbstractMicrowave-assisted synthesis of benzothiazole and benzoxazole libraries via PIFA promoted cyclocondensation of 2-aminothiophenols/2-aminophenols with aldehydes under one-pot condition in good to excellent yields was achieved. 20 compounds have been investigated for their analgesic activity and showed moderate to good activity.

Diastereoselective synthesis of cis-fused pyrano and furanobenzopyrans catalyzed by indium trichloride or triphenyl phosphonium perchlorate

Abstract Indium trichloride (InCl 3 ) and triphenyl phosphonium perchlorate (TPP) are found to be effective catalysts for the cyclization of o -hydroxyaldimines with 3,4-dihydro-2 H -pyran and 2,3-dihydrofuran at ambient temperature to afford novel pyrano and furanobenzopyran derivatives in excellent yields with high diastereoselectivity. One pot syntheses of pyrano and furanobenzopyrans from o -hydroxybenzaldehyde, aromatic amines and an enol ether under identical conditions is reported for the first time. Similarly, o -hydroxyaldimine reacted with ethyl vinyl ether to give 2-ethoxy-4- N -aryl aminobenzopyran in good yields.

Antibacterial Activity, Quantitative Structure–Activity Relationship and Diastereoselective Synthesis of Isoxazolidine Derivatives Via 1,3-Dipolar Cycloaddition of d-glucose Derived Nitrone with Olefin

The diastereoselectivity of the intermolecular 1,3‐dipolar cycloaddition reaction of d‐glucose‐derived nitrones with both cyclic and acyclic dipolarophiles were studied. The reaction of nitrone with acyclic dipolarophiles resulted in the formation of the endo adduct exclusively whereas with cyclic dipolarophiles endo adduct was obtained as the major product. Antibacterial activity was evaluated for these eighteen isoxazolidine derivatives against Staphylococcus aureus NCIM5021, Escherichia coli NCIM 2931 and Pseudomonas aeruginosa NCIM 5029 by twofold dilution technique using resazurin as the indicator dye. Quantitative structureactivity relationships were developed with fourteen and the model was validated with four data. Electronic and spatial descriptors were the major contributors in all the three quantitative structureactivity relationship equations and the statistical parameters r2, , F‐ratio and q2 were found to be satisfactory.

A New and Facile Method for the Synthesis of Nitrocarbazoles by Urea Nitrate

Abstract Urea nitrate in acetic acid is found to be an effective and mild nitrating agent for the preparation of mono nitrocarbazoles.

Synthesis of densely functionalised C-glycosides by a tandem oxy Michael addition-Wittig olefination pathway.

Wittig olefination of 5,6-dideoxy-5,6-anhydro-6-nitro-D-glucofuranose (5) triggered a concomitant cyclisation via oxy Michael addition of the C2-hydroxyl group resulting in the formation of C-vinyl glycosides with Z-olefinic geometry.