Asymmetric Addition of Allomaltol to Chalcones and Bis(arylidene)acetones: En Route to Chiral Drugs

The synthesis of enantiomerically enriched γ‐oxobutiric acid and succinic acid derivatives based on asymmetric conjugate addition of allomaltol to chalcones or bis(arylidene)acetones in the presence of readily available and recoverable C2‐symmetric tertiary amine‐squaramide organocatalyst has been developed. Ru(III)‐catalyzed oxidative transformation of pyran‐4‐ones bearing the α,β‐enone unit to enantiomerically enriched succinic acid derivatives via a one‐pot oxidative fragmentation of both the γ‐pyrone ring and activated C=C bond has been elaborated. The developed methodology was applied for scalable asymmetric synthesis of GABAB receptor agonists precursors, RAR receptor agonists and monoaminooxidase (MAO) inhibitors.