Substrate Controlled Product Divergence in Iron(III)‐Catalyzed Reactions of Propargylic Alcohols: Easy Access to Spiro‐indenyl 1,4‐Benzoxazines and 2‐(2,2‐Diarylvinyl)quinoxalines

We report herein unprecedented cascade reactions of O-propargyl-N-tosyl-amino phenols with 10 mol% FeCl3 in DCE at room temperature for 0.67-3 h to form spiro-indenyl 1,4-benzoxazines with 38-89% yields. Replacing the oxygen atom of the said substrates by NTs group followed by treatment with the same catalyst and solvent at 80 oC produced 2-(2,2-diarylvinyl)quinoxalines in 12-20 h with up to 62% yields. Mechanistic understanding provided an insight into the transformations. The use of simple substrates and environmentally benign low cost catalyst, broad substrate scope and tolerance of diverse functional groups makes the methodology inherently attractive.