A consecutive one-pot two-step approach to trifluoromethylated pyrazolo[4ʹ,3ʹ:5,6]pyrano[2,3-b]indoles promoted by molecular iodine

A facile and consecutive one-pot reaction for preparation of trifluoromethylated pyrazolo[4ʹ,3ʹ:5,6]pyrano[2,3-b]indoles promoted by molecular iodine is described. [Display omitted] •One-pot two-step to trifluoromethylated pyrazolo[4ʹ,3ʹ:5,6]pyrano[2,3-b]indoles.•Molecular iodine promoted the first conversion.•POCl3 as dehydrating reagent for intramolecular annulation.•A more consecutive approach was achieved. An one-pot two-step three-component reaction of 2-indolinone, aromatic aldehydes and 1-aryl-3-trifluoromethyl-5-pyrazolone afforded trifluoromethylated poly-heterocyclic compounds containing pyrazolo[4ʹ,3ʹ:5,6]pyrano[2,3-b]indole skeleton. This atom economic and facile manipulative reaction involved initial treatment of three-component reaction mixtures with molecular iodine, followed by intramolecular annulation reaction with POCl3 in one-pot manner without isolation. Compared with the step-wise reactions, a more consecutive approach to trifluoromethylated pyrazolo[4ʹ,3ʹ:5,6]pyrano[2,3-b]indoles was achieved.