Utilization of a new ionic liquid based on tropine as an efficient catalystfor the acceleration of the synthesis of spiro-۲-amino-۴H-pyran-oxindoles

In recent years ionic liquids(ILs) have become a promising area of concern fororganicchemists due to their distinctive properties such as high thermalstability, low vaporpressure, high load capacity, ease ofrecycling and environmental friendliness[۱]. Tropine, abicyclo structured compound, is one of the important tropane alkaloids which under the influenceof special features in main structure such as having a nitrogen atoms and hydroxyl group and itsability to form hydrogen bonds has a high potential for the synthesis of ionic liquids with highbiocompatibility. Heterocyclic systems containing pyran rings specially spiro-۲-amino-۴Hpyranshave received considerable attention due to their various biological and pharmacologicalactivities [۲]. These compounds form the structural unit of many natural products and arepotential calcium channel antagonists, also having various activities such as anti-allergy, antitumor,and anti-bacterial [۳].In this work, we wish to introduce a efficient ionic liquid based ontropine([C۸-Tropine].Cl) for the acceleration of the synthesis of thespiro-۲-amino-۴H-pyranoxindoles.The green conditions, simple catalyst preparation, straightforward separation andrecovery of the catalyst from the reaction mixture, simple work-up method requiring no specialseparation procedure, use of water as a reaction media, short reaction times, and high yields ofthe products are the significant points of interest of this study.

Keywords:

Ionic liquid , Spiro-۲-amino-۴H-pyran-oxindoles , Tropine , [C۸-Tropine].Cl.