Y. Thirupathi Reddy

3-[Benzimidazo- and 3-[benzothiadiazoleimidazo-(1,2-c)quinazolin-5-yl]-2H-chromene-2-ones as potent antimicrobial agents.

A series of 3-[benzimidazo(1,2-c)quinazolin-5-yl]-2H-chromene-2-one (6a-6f) and 3-[benzothiadiazole- imidazo(1,2-c)quinazolin-5-yl]-2H-chromene-2-one derivatives (7a-7f) that incorporate a variety of substituents at the 6- and/or 8-positions of the coumarin moieties have been synthesized utilizing cellulose sulfuric acid as an efficient catalyst under both conventional heating and microwave irradiation procedures. These analogs were evaluated for their antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Streptococcus pyogenes (Gram-positive bacteria), Escherichia Coli, Klebsiella pneumonia, Salmonella typhimurium (Gram-negative bacteria), and Aspergillus niger, Candida albicans, and Aspergillus flavus (Fungi). Two analogs, 6c (a 6,8-dichloro analog, MIC([SA]) = 2.5 μg/mL; MIC([ST]) = 2.5 μg/mL) and 7d (a 6,8-dibromo analog, MIC([ST]) = 2.5 μg/mL) were identified as potent antibacterial agents, and two analogs, 6b (a 6-bromo analog, MIC([AF]) = 10 μg/mL) and 6d (a 6,8-dibromo analog, MIC([AF]) = 15 μg/mL; MIC([CA]) = 15μg/mL), were identified as potent antifungal agents. Based on the MIC data, analogs 6b, 6c, 6d, and 7d were identified as the most potent antimicrobial agents in the series.

Synthesis and evaluation of chromenyl barbiturates and thiobarbiturates as potential antitubercular agents.

A novel series of barbiturate and thiobarbiturate analogs of 2-benzoyl-3-methyl-5-oxo-5H-furo[3,2-g]chromene-6-carbaldehydes (3a-g and 4a-d, respectively) and 6-methyl-4,8-dioxo-4,8-dihydropyrano[3,2-g]chromenes (7a-c), were synthesized and evaluated for their antitubercular activities against Mycobacterium tuberculosis H37RV, and cytotoxicity (CC(50)) in the VERO cell MABA assay. The results indicate that the furanochromene series of compounds (3a-g and 4a-d) showed only weak to moderate antitubercular activity. However, the pyranochromene analog 7b showed good antitubercular activity (IC(90): 5.9μg/mL) and cytotoxicity (CC(50): 14.27μg/mL). The antitubercular activity of 7b was superior to the antituberculosis drug, pyrazinamide (PZA; IC(90): >20μg/mL). Analog 7b was considered to be a lead compound for subsequent structural optimization.

Novel substituted (Z)-5-((N-benzyl-1H-indol-3-yl)methylene)imidazolidine- 2,4-diones and 5-((N-benzyl-1H-indol-3-yl)methylene)pyrimidine- 2,4,6(1H,3H,5H)-triones as potent radio-sensitizing agents

A series of (Z)-5-((N-benzyl-1H-indol-3-yl)methylene)imidazolidine-2,4-dione (9a-9m) and 5-((N-benzyl-1H-indol-3-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (10a-10i) derivatives that incorporate a variety of aromatic substituents in both the indole and N-benzyl moieties have been synthesized. These analogs were evaluated for their radiosensitization activity against the HT-29 cell line. Three analogs, 10a, 10b, and 10c were identified as the most potent radiosensitizing agents.

Ceric Ammonium Nitrate (CAN): An Efficient Catalyst for the Coumarin Synthesis via Pechmann Condensation using Conventional Heating and Microwave Irradiation

Abstract An efficient and convenient method for the synthesis of substituted coumarins via Pechmann condensation of different phenols with ethylacetoacetate in the presence of ammonium cerium(IV) nitrate as the catalyst in a solvent- free media using both conventional heating and microwave irradiation.

Cellulose Sulfuric Acid: An Efficient Biodegradable and Recyclable Solid Acid Catalyst for the One-Pot Synthesis of 3,4-Dihydropyrimidine-2(1H)-ones

Abstract Biosupported cellulose sulfuric acid has been found to be an efficient solid acid catalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones. The advantages of this method are avoidance of harsh reaction conditions, ecofriendly chemistry, operational simplicity, high yield, and reusable catalyst.

Expeditious Pechmann Condensation by Using Biodegradable Cellulose Sulfuric Acid as a Solid Acid Catalyst

A facile synthesis of coumarins was performed in excellent yields via Pechmann condensation by using different type of phenols and ethylacetoacetates under solvent–free media using both conventional method and microwave irradiation in short reaction times is described. The reaction workup is very simple, and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent reactions.

Cellulose Sulfuric Acid: An Efficient Biodegradable and Recyclable Solid Acid Catalyst for the Synthesis of 1-Oxo-hexahydroxanthene

Abstract A series of 1-oxo-hexahydroxanthene derivatives was synthesized at room temperature in solid state from substituted salicylaldehydes and substituted 1,3-hexanediones in the presence of a catalytic amount of cellulose sulfuric acid. The results showed that the reaction performed under solid-state conditions was benign to the environment, with higher yields and more convenient workup.

CuPy2Cl2: A Novel and Efficient Catalyst for Synthesis of Propargylamines Under the Conventional Method and Microwave Irradiation

Abstract CuPy2Cl2 is an efficient catalyst for the preparation of propargylamines via three-component coupling reaction of aromatic aldehydes, amines, and aromatic alkynes stirred at 95 °C without using any solvent to afford the corresponding products in good yields. The reaction mixture was irradiated at 450 W in a microwave oven to furnish the expected products in excellent yields.

Cellulose Sulfuric Acid: Novel and Efficient Biodegradable and Recyclable Acid Catalyst for the Solid-State Synthesis of Thiadiazolo Benzimidazoles

Abstract An efficient method for the synthesis of 2-substituted benzimidazoles has been developed. In this method, benzo[c][1,2,5]thiadiazole-4,5-diamine was condensed with different aldehydes in the presence of cellulose sulfuric acid under solvent-free conditions by simple physical grinding of reactants using a mortar and pestle at room temperature. The methodology is mild, high-yielding, and green, and the catalyst could be easily recycled.

Sulfamic Acid: An Efficient, Cost-Effective, and Reusable Solid Acid Catalyst for the Synthesis of 1,8-Naphthyridines Under Solvent-Free Heating and Microwave Irradiation

Abstract An efficient and convenient method is described for the synthesis of 1,8-naphthyridines in excellent yields by condensation of 2-aminonicotinaldehyde with various active methylene compounds in the presence of sulfamic acid as the catalyst in a solvent-free media using both conventional heating and microwave irradiation.