Enantioselective Dearomative [4+2] Cycloaddition Reaction of 1‐Naphthols with In‐Situ Generated ortho‐Quinone Methides

Abstract

AbstractWe disclose a catalytic, enantioselective dearomative reaction of non‐functionalized 1‐naphthols, which poses a synthetic challenge to organic chemists because of the relative ease of rearomatization via the elimination of a proton. In this work, the direct dearomatization of non‐functionalized 1‐naphthols was achieved through a chiral phosphoric acid (CPA) catalyzed enantioselective dearomative [4+2] cycloaddition reaction with in‐situ generated ortho‐quinone methides (o‐QMs). The reported convergent method allows the use of readily available simple 1‐naphthols without pre‐functionalization, furnishing a variety of naphthopyran derivatives in good yields (up to 96 %) and moderate to excellent enantioselectivities (up to >99 % ee) under mild reaction conditions. The observed regio‐, diastereo‐, and enantioselectivities are the keys to the success of the current strategy utilizing o‐QM as a diene surrogates, in combination with CPA catalysis.