Romesh C. Boruah

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.

A facile synthesis of annelated pyridines from β-formyl enamides under microwave irradiation

Abstract The condensation of β-formyl enamides with cyanomethylenes under microwave irradiation is catalysed by basic alumina to afford fused pyridines in excellent yields.

A Facile dehydration and beckmann rearrangement of oximes with aluminium iodide

Abstract Aluminium iodide has been developed as an efficient reagent for the conversion of aldoxims to nitriles and the Beckmann rearrangement of ketoximes to anilides.

An efficient conversion of conjugated oximes into substituted pyridines under Vilsmeier conditions

Abstract A facile synthesis of a pyrido fused steroidal D-ring and functionalised pyridine is described.

Alumina-promoted fast solid-phase Michael addition of enamines with conjugated enones under microwave irradiation

Abstract A fast alumina-promoted solid-phase Michael addition of enamines to conjugated enones is described under microwave irradiation in high yields. The 1,5-diketo Michael adducts have been converted into a novel class of 1′,2′-diazepino(17,16-d′) steroids.

An efficient cleavage and fries rearrangement of esters with aluminium triiodide

Abstract Aluminium triiodide efficiently cleaved esters to carboxylic acids and converted phenyl benzoate to o- and p-hydroxybenzophenones via Fries rearrangement.

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.

A facile three-component solid phase synthesis of steroidal A-ring fused pyrimidines under microwave irradiation

The preparation of ring-A fused pyrimidines at the steroidal 2,3-position is herein described. The novel steroidal pyrimidines were prepared from the solid phase three-component reaction of 2-hydroxymethylene-3-keto steroids, arylaldehydes and ammonium acetate under microwave irradiation.

Synthesis of dihydro- and tetrahydroisoxazolo[3',4':3,4]pyrrolo[1,2-a]indoles via intramolecular cycloadditions: a novel class of mitomycin analogues

Abstract A novel class of dihydro- and tetrahydroisoxazolo [3′,4′:3,4]pyrrolo[1,2-a]indoles are synthesized via intramolecular nitrone and nitrile oxide cycloaddition reactions.

Carbon–Carbon Bond Cleavage Reaction: Synthesis of Multisubstituted Pyrazolo[1,5-a]pyrimidines

A new carbon-carbon bond cleavage reaction was developed for the efficient synthesis of multisubstituted pyrazolo[1,5-a]pyrimidines. This base induced reaction of 1,3,5-trisubstituted pentane-1,5-diones and substituted pyrazoles afforded good yields of the pyrazolo[1,5-a]pyrimidines.