Chiral Hydrogen-Bond Donor and Gold(I) Cocatalysis Enables Enantioselective Dearomative Spirocyclization of Naphthols
Timur Adrianov1, Eric N Jacobsen1
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.
Abstract:
We report the enantioselective gold(I)-catalyzed dearomative spirocyclization of naphthols enabled by the cooperative effect of chiral dual hydrogen-bond donors (HBDs). The reaction affords carbocyclic and heterocyclic spirocycles bearing a quaternary stereocenter with high enantioselectivity (up to 99% enantiomeric excess). Kinetic analysis supports a mode of catalysis wherein two molecules of a monomeric urea cocatalyst activate the neutral gold(I) sulfonate complex via anion abstraction to induce enantioselectivity and rate acceleration in the cyclization reaction. A systematic investigation of ligand effects identified a correlation between the electronic properties of the gold(I) phosphine ligand and the observed enantioselectivity.
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