4‐Aryl‐1H‐isochromenes Synthesis from Triol Derivatives through Brønsted Acid‐Catalyzed Pinacol Rearrangement/Intramolecular Cyclization Sequence

Abstract

4‐Aryl‐1H‐isochromene derivatives have been successfully synthesized by Brønsted acid‐catalyzed pinacol rearrangement/intramolecular cyclization of the substituted 1‐(2‐(hydroxymethyl)phenyl)‐2‐arylethane‐1,2‐diols. The reaction generally proceeded with low catalyst loading of trifluoromethanesulfonic acid (5 mol%) for short reaction times (10‐20 min) to furnish the desired 4‐aryl‐1H‐isochromenes which were subsequently hydrogenated to 4‐aryl‐isochromans with up to 90% yield. Moreover, oxidation of the resulting 4‐aryl‐isochroman provided the desired 4‐aryl‐isochroman‐1‐one in good yield.