Enantioselective Copper-Catalyzed Dearomative Spiroannulation of β-Naphthols or Indoles with Yne-Allylic Esters

Abstract

Catalytic asymmetric dearomatization reactions of α-unsubstituted β-naphthols are very challenging due to the high energy barrier resulting from the loss of aromaticity. Herein, we describe an example of enantioselective catalytic dearomative spiroannulation with yne-allylic esters. The success of this reaction relied on the copper-catalyzed remote asymmetric strategy using yne-allylic esters as the bis-electrophilic reagents. This transformation features mild reaction conditions, broad functional group tolerance, and an extensive substrate scope, thereby facilitating the efficient construction of an array of enantioenriched naphthalene-2-one and spiroindolenine derivatives. Experimental studies and density functional theory calculations establish the reaction pathway and origin of stereoselectivity.

Copper-Catalyzed Dual Remote Asymmetric Vinylogous Alkynylallylic Substitution of Yne-Allylic Esters with Coumarins

“…The copper allenylidene complex as the key reactive intermediate was applied in this reaction mode. Recently, a new copper–vinylvinylidene complex was reported by Fang et al, He et al, Xu et al, our group, and other groups, which formed from the substrate that when an extended CC bond or aryl group assembly into propargylic alcohol derivatives (Scheme a). In particular, the He group described an elegant copper-catalyzed enantioselective propargylic amination of yne-allylic esters with amines at the γ position of the copper–vinylvinylidene complex to yield chiral 1,4-enyne products. , Xu et al and our group independently reported the copper-catalyzed remote asymmetric alkynylallylic substitution of yne-allylic esters with 1,3-dicarbonyl compounds or sodium sulfinates at the ε position of the copper–vinylvinylidene complex.…”