π-Extended C2-Symmetric Double NBN-Heterohelicenes with Exceptional Luminescent Properties.

Two novel B,N-embedded double heterohelicenes, Ph-NBNDH and Naph-NBNDH, with intensively twisted quasi-C2 symmetrical structures are synthesized for the first time via a highly regioselective intramolecular Scholl reaction. The π-extended skeletons render them with exceptional physical properties, such as the highest fluorescence quantum yields up to 0.83 among multiple helicenes. Moreover, the isolated (M,M)- and (P,P)-enantiomers of Naph-NBNDH deliver intense circularly polarized luminescence. As the emitting layer, Ph-NBNDH exhibits strong electroluminescence at high working voltage.

Successive Annulation to Fully Zigzag-Edged Polycyclic Heteroaromatic Hydrocarbons with Strong Blue-Green Electroluminescence.

A Brønsted-acid-promoted alkyne benzannulation approach was developed to synthesize the amino-substituted dibenze[ a, j]anthracence derivatives in excellent yields, which were directly converted to fully zigzag-edged polycyclic heteroaromatic hydrocarbons via a nitrogen-directed electrophilic borylation. As the dopant in a blue-green electroluminescent device, the resulted compound exhibited relatively high stability.

A simple, one pot synthesis of furo[3,2-c]chromenes and evaluation of antimicrobial activity.

Synthesis of a number of 2-cyano-4-oxo-3-phenyl-3,4-dihydro-2H-furo[3,2-c]chromene-2-carboxylate compounds (5) have been accomplished by a simple, multicomponent one pot reaction and evaluated for in vitro antimicrobial activity against different Gram-positive and Gram-negative bacterial strains. The outcome of the screening study showed that compound 5c exhibited promising activity against Micrococcus luteus MTCC 2470 and Klebsiella planticola MTCC 530. Whereas, compound 5g exhibited excellent activity against Bacillus subtilis MTCC 121, Micrococcus luteus MTCC 2470, Klebsiella planticola MTCC 530, Escherichia coli MTCC 739 and displayed a moderate activity against Staphylococcus aureus MTCC 96 and Candida albicans MTCC 3017 when compared with Ciprofloxacin (standard control).

One pot oxidative N-S bond formation to access 2-sulfenylimine chromenes.

The synthesis of 2-sulfenylimine chromene compounds (8) is accomplished by reacting benzaldehyde (1), malanonitrile (2) and dimedone (3) followed by sequential addition of N-chlorosuccinimide and thiophenols to the in situ formed 2-amino-4(H) chromenes (4) in a one pot, catalyst free, five component reaction in toluene medium. When aniline was employed as the nucleophile in place of thiophenol, the formation of hexahydrobenzofuran-2-N-phenyl carboxamide derivatives (5) was observed. Excellent yields, simple reaction conditions and high compatibility are the advantages of this protocol.

Synthesis and evaluation of novel fluorinated pyrazolo-1,2,3-triazole hybrids as antimycobacterial agents.

A library of novel 3-trifluoromethyl pyrazolo-1,2,3-triazole hybrids (5-7) were accomplished starting from 5-phenyl-3-(trifluoromethyl)-1H-pyrazol-4-amine (1) via key intermediate 2-azido-N-(5-phenyl-3-(trifluoromethyl)-1H-pyrazol-4-yl)acetamide (3) through click chemistry approach. Thus obtained compounds in 5-7 series were evaluated for in vitro antimycobacterial activity against Mycobacterium smegmatis (MC(2) 155) and also verified the cytotoxicity. These studies engendered promising lead compounds 5q, 7b and 7c with MIC (µg/mL) values 15.34, 16.18 and 16.60, respectively. Amongst these three compounds, 2-(4-(4-methoxybenzoyl)-1H-1,2,3-triazol-1-yl)-N-(5-phenyl-3-(trifluoromethyl)-1H-pyrazol-4-yl) acetamide (5q) emerged as the most promising antitubercular agent with lowest cytotoxicity against the A549 cancer cell line. This is the first report to demonstrate the pyrazolo triazole hybrids as potential antimycobacterial agents.

One-pot catalyst free synthesis of novel kojic acid tagged 2-aryl/alkyl substituted-4H-chromenes and evaluation of their antimicrobial and anti-biofilm activities.

A number of 3-hydroxy-6-(hydroxymethyl)-2-(2-phenyl-4H-chromen-4-yl)-4H-pyran-4-ones (3) have been synthesized in a one pot catalyst free reaction of 2-hydroxy chalcone (1) with kojic acid (2) in toluene at reflux temperature and evaluated for antimicrobial and anti-biofilm activities. Compounds 3a, 3e, 3f, 3l showed potent antimicrobial activity against Staphylococcus aureus MLS-16 MTCC 2940, Bacillus subtilis MTCC 121 and Escherichia coli MTCC 739, whereas 3b and 3k exhibited excellent activity against Bacillus subtilis MTCC 121 and Escherichia coli MTCC 739, while 3g showed promising activity against Bacillus subtilis MTCC 121 and Escherichia coli MTCC 739. On the other hand, compounds 3a, 3b and 3l showed very good anti-biofilm activity and 3g showed moderate activity against Bacillus subtilis MTCC 121. Whereas, compounds 3a and 3f showed moderate activity against Escherichia coli MTCC 739, while compounds 3a, 3b, 3k and 3l displayed similar activity against Staphylococcus aureus MLS-16 MTCC 2940.

Regioselective synthesis of 3-benzyl substituted pyrimidino chromen-2-ones and evaluation of anti-microbial and anti-biofilm activities.

Regioselective synthesis of a number of highly functionalized 3-benzylpyrimidino chromen-2-ones (4) were accomplished in a one pot three component reaction in acetic acid and determined their anti-microbial and anti-biofilm activities. Compounds 4o and 4p showed an excellent anti-microbial activity against Micrococcus luteus MTCC 2470 at a par with standard control (Ciprofloxacin) and exhibited best activity against Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121. Further, compounds 4h, 4i, 4m, 4n and 4q showed promising activity against Micrococcus luteus MTCC 2470, Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121. Whereas, compounds 4m showed very promising biofilm inhibition activity against Staphylococcus aureus MLS 16 MTCC 2940 and 4o, 4p showed very potent activity against Staphylococcus aureus MTCC 96 at a par with Ciprofloxacin used as standard control.