Vishnu K. Tandon

AN EFFICIENT ONE POT SYNTHESIS OF 1,3,4-OXADIAZOLES

Various 1,3,4-oxadiazoles have been synthesized in excellent yields by BF3ċEt2O promoted cyclodehydration of 1,2-diacyl and diaroyl hydrazines prepared in situ from corresponding acid chlorides and hydrazine.

2,3-Disubstituted-1,4-naphthoquinones, 12H-benzo[b]phenothiazine-6,11-diones and related compounds: Synthesis and Biological evaluation as potential antiproliferative and antifungal agents

A series of 2-chloro-3-arylsulfanyl-[1,4]naphthoquinones (2), 2,3-bis-arylsulfanyl-[1,4]naphthoquinones (3) and 12H-benzo[b]phenothiazine-6,11-diones and their analogs 6-8 were synthesized and evaluated for their antiproliferative activity against human cervical cancer (HeLa) cells. Compounds 3a and 3b were found to possess most potent antiproliferative and cell killing ability. Compounds 1-8 were also evaluated for antifungal activities. The structure-activity relationship of these compounds was studied and the results show that compound 2a (MIC(50)=1.56 microg/mL) exhibited in vitro potent antifungal activity compared to the clinically useful antifungal drug Fluconazole (MIC(50)=2.0 microg/mL) against Sporothrix. schenckii. Compound 2a (MIC(50)=1.56 microg/mL) also exhibited same antifungal activity compared to clinically useful drug Amphotericin-B (MIC(50)=1.56 microg/mL) against Trichophyton. mentagraphytes.

'On water' assisted synthesis and biological evaluation of nitrogen and sulfur containing hetero-1,4-naphthoquinones as potent antifungal and antibacterial agents.

2-chloro-3-(4-methylpiperazin-1-yl)naphthalene-1,4-dione (3a), 2-chloro-3-(pyrrolidin-1-yl)naphthalene-1,4-dione (3b), 2-chloro-3-(piperidin-1-yl)naphthalene-1,4-dione (3c), 2-chloro-3-morpholinonaphthalene-1,4-dione (3d), 2-chloro-3-(2-phenylhydrazinyl)naphthalene-1,4-dione (3e), 2-(allylamino)-3-chloronaphthalene-1,4-dione (3f), 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)acetic acid (3g), 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)succinic acid (3h), methyl 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)acetate (3i), 2-chloro-3-(2-mercaptoethylthio)naphthalene-1,4-dione (3j), 3-hydroxy-4-methyl-4H-naphtho[2,3-b][1,4]thiazine-5,10-dione (3k) and compounds 3l-q have been synthesized by a green methodology approach using water as solvent and evaluated for their antifungal and antibacterial activity. The antifungal profile of 3a-n indicated that compounds 3a-d, 3j, 3e and 3k have potent antifungal activity. Amongst the most promising antifungal compounds, 3a-g, 3j, 3k showed better antifungal activity than clinically prevalent antifungal drugs Fluconazole and Amphotericin-B against Trichophyton mentagraphytes and compounds 3j and 3k have been found to be lead antifungal bicyclic and tricyclic 1,4-naphthoquinones. Compound 3k also exhibited pronounced antibacterial activity.

Micelles catalyzed chemoselective synthesis 'in water' and biological evaluation of oxygen containing hetero-1,4-naphthoquinones as potential antifungal agents.

Various oxygen containing 1,4-naphthoquinone derivatives have been synthesized chemoselectively by an economical, viable green methodology approach using water as solvent with or without surfactants such as Triton X-100, SDS, LD (laundry detergent), and TBAB, a phase transfer catalyst and evaluated for their in vitro antifungal and antibacterial activity. The antifungal profile of 3, 4a, 4b, and 6 indicated that compounds 3a, 3b, 4b, 6a, and 6c have potent antifungal activity compared to clinically prevalent antifungal drugs Fluconazole and Amphotericin-B against Sporothrix schenckii, Trichophyton mentagraphytes, and Candida parapsilosis and compound 3b has been found to be a lead antifungal agent for further study.

Phenethylamine in a rigid framework : synthesis, stereochemistry and reactions of cis and trans-4-amino-2,3,4,5-tetrahydro-1-benzoxepin-5-ols and their derivatives

Abstract cis - and trans - amino alcohols 1a and 2a and their derivatives have been synthesised and their stereochemistry studied. Stereochemical studies have shown that cis -isomer is thermodynamically more favoured than the trans -isomer.

Facile and efficient synthesis of 1,4-benzodiazepines from 1,4-naphthoquinones

Concise intramolecular cyclization reaction of 2,3-diamino-1,4-dihydro-naphthalenediones 4 and 7 in anhydrous K 2 CO 3 /Et 3 N and EtOH yielded novel 1,4-benzodiazepines 5 and 6 fused with 1,4-naphthoquinone nucleus.

Nickel-promoted Favorskii type rearrangement of cyclic α-bromoketones

Favorskii type rearrangement of cyclic α-bromo ketones 2 is promoted by NiCl 2 in refluxing methanol, giving the rearranged carboxylic acid ester 3 in excellent yields. The reaction of 4-bromo-2,3,4,5-tetrahydronaphth [2,1-b]oxepin-5-one (5) and its regioisomer 8 with NiCl 2 in MeOH resulted in Favorskii rearranged carboxylic acid esters 6 and 9 respectively.

Diethyl zinc catalyzed diastereoselective addition of ketenes to (S)-(+)-3-hydroxytetrahydrofuran

The reaction of (S)-(+)-3-hydroxytetrahydrofuran with phenyl methyl ketene in presence of n-BuLi and Et2Zn results in the formation of the diastereomeric esters (SS+SR) with a high degree of diastereoselectivity (98:2).

Synthesis and evaluation of 2-heteroaryl and 2,3-diheteroaryl-1,4-naphthoquinones that potently induce apoptosis in cancer cells

This article describes the preparation of 2-heteroaryl and 2,3-diheteroaryl-1,4-naphthoquinones by an environmentally benign short synthetic route with the goal of finding 1,4-naphthoquinone derivatives that induce apoptosis in cancer cells. We have identified three most active naphthoquinones 10, 12 and 15 that potently induce apoptosis in human cervical carcinoma (HeLa) cells. One of these three compounds perturbed both microtubule and actin filaments.

p-Toluenesulfonylmethyl Isocyanide: A Versatile Synthon in Organic Chemistry

Abstract TosMIC, a versatile synthon in organic chemistry, has been extensively used for the synthesis of a wide variety of small, medium and large ring heterocycles. It has immense implications in the synthesis of nitriles, aldehydes, ketones, alkanes, cyclophanes and large number of natural products. Several drug intermediates and pharmacologically active compounds have been synthesized from TosMIC. In addition, chiral TosMIC analogs have been synthesized and employed for synthesis of optically active compounds.