Formation of 8‐Hydroxyphenanthridines by Microwave‐Mediated IMDAF Reactions; Synthesis Directed towards Lycorine Alkaloids

8‐Hydroxyphenathridines have been synthesized efficiently from N‐propargyl‐ortho‐furylanilines employing microwave‐mediated one‐pot intramolecular Diels–Alder reaction on furans (IMDAF) reaction and subsequent aromatization. The 8‐hydroxyphenathridines were also subjected to further functionalization; O‐alkylation and conversion to the corresponding triflate followed by Suzuki coupling. N‐Propargyl‐7‐furylindole and the corresponding indoline also underwent smooth IMDAF cyclization to give, after rearomatization, 7H‐pyrrolo[3,2,1‐de]phenanthridin‐9‐ol or the 4,5‐dihydro analog. These cyclization products could be further functionalized, i.e. O‐ or N‐alkylation and oxidation at C‐6. The oxidation could lead to 6‐oxo derivatives or pyrrolo[3,2,1‐de]phenanthridin‐6‐ium salts depending on the reaction conditions and structure of the substrate. The 9‐oxy‐pyrrolophenanthridines synthesized are structurally closely related to bioactive lycorine alkaloids. 8‐Hydroxyphenathridines have been synthesized from N‐propargyl‐ortho‐furylanilines by a one‐pot intramolecular Diels–Alder reaction on furans (IMDAF) reaction and aromatization. N‐Propargyl‐7‐furylindol(in)es also underwent IMDAF cyclization to give (4,5‐dihydro)7H‐pyrrolo[3,2,1‐de]phenanthridin‐9‐ols These are structurally closely related to bioactive lycorine alkaloids.