Sudipta Ponra

Green approach to highly functionalized thiopyrano derivatives via domino multi-component reaction in water

A green, operationally simple and highly efficient one pot three-component approach for the synthesis of thiopyrano[2,3-b]indole-3-carbonitrile, thiopyrano[2,3-b]thiochromene-3-carbonitrile and dihydrothiochromeno[2,3-b]thiochromene derivatives has been developed by the domino reaction of indoline-2-thione or 4-hydroxy-2H-thiochromene-2-thione with aldehyde and malononitrile or dimedone in water at 100 °C. The significant advantages of this protocol are highlighted by short reaction time, excellent yields and formation of three new bonds and a stereocenter in one operation from easily available starting materials.

Brønsted acid-promoted synthesis of common heterocycles and related bio-active and functional molecules

Various heterocyclic systems based on natural and unnatural biologically active products were synthesized by Bronsted acid-promoted cyclization. We have made an attempt to summarize the progress made in this area during the period 2005 to 2015. This article describes the synthetic routes of these heterocycles that involve a Bronsted acid-promoted cyclization as a crucial step or Bronsted acids as co-catalysts with other transition metals.

Synthesis of novel pyrano[3,2-f]quinoline, phenanthroline derivatives and studies of their interactions with proteins: An application in mammalian cell imaging

A series of tri-cyclic pyrano[3,2-f]quinoline and phenanthroline derivatives have been synthesized by a HCl-mediated 6-endo-trig Michael type ring closure reaction of 6-amino-5-(3-hydroxy-3-methylbut-1-ynyl)-2H-chromen-2-one in excellent yields. The process is very simple, facile and inexpensive and can provide a diverse range of substituted quinoline derivatives from simple and easily available starting materials. Moreover, the synthesized derivatives exhibit staining property to the cultured HeLa cells after fixing and can be used as fluorophores which can bind with protein molecule.