Bimetallic Catalytic Asymmetric Tandem Reaction of β‐Alkynyl Ketones to Synthesize 6,6‐Spiroketals

The enantioselective tandem reaction of β,γ‐unsaturated α‐ketoesters with β alkynyl ketones was realized by a bimetallic catalytic system of achiral AuIII salt and chiral N,N'‐dioxide‐MgII complex. The cycloisomerization of β‐alkynyl ketone and asymmetric intermolecular [4+2] cycloaddition with β,γ‐unsaturated α‐ketoesters subsequently occured, providing an efficient and straightforward access to chiral multifunctional 6,6‐spiroketals in up to 97% yield, 94% ee and > 19/1 d.r.. Besides, a catalytic cycle was proposed based on the results of control experiments.

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