Kommuri Shekarrao

A microwave promoted solvent-free approach to steroidal quinolines and their in vitro evaluation for antimicrobial activities.

The preparation of A-ring and D-ring fused steroidal quinolines is described from one-pot reaction of steroidal β-bromovinylaldehydes and arylamines in solvent-free and catalyst-free condition under microwave irradiation. The antimicrobial activities of the compounds were tested by agar diffusion assay and broth macro dilution method. Compounds 7a, 7e and 7g-h showed promising in vitro activity when tested against fungal pathogen Aspergillus niger whereas compounds 7e-h and 7j showed promising activity when tested against fungal pathogen Candida albicans. Compounds 7c and 7f showed potent inhibition against the growth of Gram negative bacteria Pseudomonas aeruginosa and compounds 7e, 7g-h and 7j inhibited the growth of tested Gram positive bacteria Bacillus subtilis and Staphylococcus aureus.

Ruthenium(II)-Catalyzed Alkene C–H Bond Functionalization on Cinnamic Acids: A Facile Synthesis of Versatile α-Pyrones

An inexpensive ruthenium(II) complex enabled oxidative annulation of alkynes by using cinnamic acid derivatives to provide diversely decorated multisubstituted α-pyrones.

Microwave-assisted palladium mediated efficient synthesis of pyrazolo[3,4-b]pyridines, pyrazolo[3,4-b]quinolines, pyrazolo[1,5-a]pyrimidines and pyrazolo[1,5-a]quinazolines

An efficient method was developed for the synthesis of pyrazole fused heterocycles via the palladium-catalyzed solvent free reaction of β-halovinyl/aryl aldehydes and 3-aminopyrazoles/5-aminopyrazoles under microwave irradiation in good yields. This method is applicable for the efficient synthesis of a wide range of substituted pyrazolo[3,4-b]pyridines, pyrazolo[3,4-b]quinolines, pyrazolo[1,5-a]pyrimidines and pyrazolo[1,5-a]quinazolines. Four of the synthesized pyrazole fused compounds showed in vitro cytotoxic activities almost comparable to the drug doxorubicin against the cervical HeLa cancer cell line and prostate DU 205 cancer cell line.

Efficient synthesis of isoquinolines and pyridines via copper(I)-catalyzed multi-component reaction

A wide range of 3-substituted isoquinolines, steroidal pyridines, 5,6-dihydrobenzo[f]isoquinolines and 1,6-naphthyridine were synthesized in good yield via a ligand-free copper-catalyzed three-component reaction of β-halovinyl/aryl aldehyde, aromatic/aliphatic terminal alkyne and tert-butylamine/benzamidine in DMF under microwave irradiation. A catalyst-free reaction of ortho-alkynyl aryl/vinyl aldehydes with benzamidine under microwave irradiation also provided the 3-substituted isoquinoline and substituted pyridine derivatives in excellent yield.

Palladium-catalyzed multi-component synthesis of steroidal A- and D-ring fused 5,6-disubstituted pyridines under microwave irradiation

The preparation of steroidal A-, D-ring fused 5,6-disubstituted pyridines and nonsteroidal substituted pyridines is described form Pd(OAc)2 catalyzed multi-component reaction of steroidal/nonsteroidal β-halovinyl aldehyde, alkyne and benzylamine in solvent-free condition under microwave irradiation.

Palladium mediated regioselective intramolecular Heck reaction: synthesis of 1,3,4-trisubstituted pyrazolo[3,4-b]pyridines, 3H-pyrazolo[3,4-c]isoquinolines and 3H-pyrazolo[4,3-f][1,7]naphthyridines

An efficient method was developed for the synthesis of 1,3,4-trisubstituted pyrazolo[3,4-b]pyridines, 3H-pyrazolo[3,4-c]isoquinolines and 3H-pyrazolo[4,3-f][1,7]naphthyridines via intramolecular Heck reactions of imine derivatives of β-halovinyl/aryl aldehydes and 5-aminopyrazoles. This palladium acetate catalyzed reaction afforded good yields of these pyrazolo fused compounds under thermal conditions in the presence of xantphos as the ligand.