Indium(III) chloride catalyzed in situ generation of enamines and cyclization with imines: a novel route for synthesis of hexahydroxanthene-9-N-arylamines

A simple, efficient, and novel method has been developed for the synthesis of hexahydroxanthene-9-N-arylamine derivatives through a one-pot reaction of cyclohexanone and morpholine with salicylaldehyde imines in the presence of indium(III) chloride as a catalyst. 1-(4-Morpholino)-cyclohexene enamine prepared in situ from cyclohexanone and morpholine in presence of 20 mol% InCl3 in acetonitrile under reflux condition was used without further purification, for the cyclization reaction with salicylaldehyde Schiffʹs bases.