Pallabi Borah

Intramolecular 1,3-dipolar cycloaddition reactions in the synthesis of complex annelated quinolines, α-carbolines and coumarins

In this study, we report the synthesis of several novel dihydroisoxazole-, tetrahydroisoxazole- and dihydropyrazole-fused pyrido[2,3-b]quinolines, α-carbolines, and pyrido[2,3-c]coumarins, respectively, from simple precursors and by exploring intramolecular 1,3-dipolar cycloaddition reactions involving nitrile oxides, nitrones, and nitrile imines as 1,3-dipoles.

An efficient one-pot three-component reaction for the synthesis of novel functionalized pyrano[3,2-c]coumarins catalyzed by Na2CO3 in aqueous medium

An efficient green method for the synthesis of novel functionalized pyrano[3,2-c]coumarins from a one-pot three-component reaction of 4-hydroxycoumarins, dialkylacetylenedicarboxylates and alkyl acetonitriles catalyzed by Na2CO3 in aqueous medium was developed. The pure products were obtained in high yield from a simple work-up procedure.

Synthesis of 5-alkylated barbituric acids and 3-alkylated indoles via microwave-assisted three-component reactions in solvent-free conditions using Hantzsch 1,4-dihydropyridines as reducing agents

Reaction of barbituric acids with aldehydes and dihydropyridines in one pot under microwave (MW) irradiation in the absence of solvent, affords 55–82% of the 5-benzylated barbituric acids. Use of alkyl nitriles or barbituric acids with indole-3-aldehyde and dihydropyridine (DHP) afforded 3-alkylated indoles in 57–76 % yield. In each case DHPs are converted to pyridines.

Synthesis of Functionalized Dihydrofurocoumarin Derivatives from 3-Aminoalkyl-4-hydroxycoumarin

Abstract Some dihydrofuro-fused coumarin derivatives were synthesized from 3-aminoalkyl-4-hydroxycoumarin via in situ generation of N-ylide. The 3-aminoalkylated 4-hydroxycoumarin derivatives were synthesized from one-pot, three-component reaction of 4-hydroxycoumarin, aryl aldehydes, and secondary amines in ethanol at room temperature. Again, when salicylaldehyde was employed instead of benzaldehyde, interestingly pyranocoumarins were obtained. The reaction protocol can be further explored toward the synthesis of many other heterocyclic fused dihydrofurans. GRAPHICAL ABSTRACT

Microwave-assisted one-pot multi-component reaction: synthesis of novel and highly functionalized 3-(pyranyl)- and 3-(dihydropyridinyl)indole derivatives

One-pot multi-component reaction of 3-cyanoacetyl indole, aromatic aldehydes and ethyl acetoacetate in the presence of

Synthesis of some tetrazole fused pyrido[2,3-c]coumarin derivatives from a one-pot three-component reaction via intramolecular 1,3-dipolar cycloaddition reaction of azide to nitriles

\hbox {InCl}_{3}/\hbox {NH}_{4}

DMSO and iodine mediated reaction of 4-hydroxycoumarins and aldehydes/aryl methyl ketones: synthesis of furo[3,2-c]coumarins

InCl3/NH4OAc under microwave irradiation for 2–7 min afforded novel and highly functionalized 3-(pyranyl)- and 3-(dihydropyridinyl)indole derivatives, respectively, in good yield.

Synthesis of some novel spiro substituted pyrido[2,3-c]coumarins by exploring ‘tertiary amino effect’ reaction strategy

Abstract Some novel 5-aminoalkylbarbituric acids and corresponding chromene derivatives were synthesized via a one-pot, three-component Mannich reaction starting from 1,3-dimethylbarbituric acid, arylaldehydes, and amines. GRAPHICAL ABSTRACT