Thiourea as Bifunctional Hydrogen Bond Donor and Brønsted Base Catalyst for Green One-Pot Synthesis of 2-Aryl/Heteroaryl/Styryl Benzothiazoles in the Aqueous Medium under Ultrasound Irradiation.

A green organocatalysis cascade strategy using thiourea in catalytic amounts as both a hydrogen bond donor and a Brønsted base bifunctional catalyst was utilized to synthesize a series of 2-aryl/heteroaryl/styryl benzothiazole derivatives. This strategy involved an ultrasound-irradiated one-pot two-component reaction between substituted aldehydes and 2-amino thiophenols in an aqueous medium at 60 °C, using air as an oxidant. At the gram-scale, this protocol yielded 87% of the desired product, making it suitable for production at a larger scale. This green and mild protocol offers excellent yields, cost-effectiveness, atom economy, step economy, and a simple operation that does not require extra purification steps. Furthermore, the catalyst is easily recoverable and can be used for up to five cycles without a significant loss of any activity.

Tandem Protocol for the Synthesis of Pyrano[3,2-c]quinolone Derivatives Using Taurine as a Green Bio-Organic Catalyst in Aqueous Medium.

A series of pyrano[3,2-c]quinolone derivatives has been synthesized in the presence of taurine (2-aminoethanesulfonic acid) as a green bio-organic catalyst and water as the solvent. The target compounds were synthesized through the three-component reaction between aldehydes, malononitrile/ethylcyanoacetate, and 4-hydroxy-1-methyl-2(1H)-quinolone. The advantages of this protocol are excellent yields of products, short reaction times, cost efficiency, atom economy, and a simple work-up procedure with no need for extra purification techniques. Moreover, the catalyst can be easily recovered and reused for up to three cycles without losing any significant activity.

Antimicrobial studies, synthesis and characterization of novel 1-nitro-10H-phenothiazine bearing sulfone/nucleoside moieties.

The current research article involves one pot synthesis of novel substituted 1-nitro-10H-phenothiazines via Smiles rearrangement. These substituted phenothiazines undergo oxidation to yield 10H-phenothiazine-5,5-dioxides (sulfones) while on treatment with ß-D-ribofuranose-1-acetate-2,3,5-tribenzoate yield ribofuranosides. These compounds were screened for their antimicrobial vitalities (in vitro) against selected strains of bacteria and fungi. The characterization of synthesized compounds was done by elemental and spectral studies.

Synthesis and antitubercular screening of some novel 4H-1,4- benzothiazines and their sulfones under environment benign solvent free conditions as future anti-tubercular agents.

Some novel analogs of 4H-1,4-benzothiazines were synthesized under environmentally benign solvent free conditions by one pot oxidative cyclocondensation of substituted 2- aminobenzenthiols with compounds having active methylene group and then converted in to sulfones. These compounds were examined as antitubercular agents against Mycobacterium tuberculosis H37Rv using REMA plate method. The best results have MICs from 6.4 to 8.8 µg/mL, comparable to phenothiazines. IR, NMR and mass spectral investigations are included for structural elucidation.