Bio-Catalytic Bis-Michael Reaction for Generating Cyclohexanones with a Quaternary Carbon Center Using Glucoamylase

Bio-catalytic bis-Michael reaction for the construction of quaternary carbon centers is reported. Glucoamylase from Aspergillus niger (AnGA) was used as a sustainable and eco-friendly catalyst. Various highly substituted trans-cyclohexanones with a quaternary carbon center were obtained with yields of up to 92%. As a novel case of enzyme promiscuity, this work provides a bio-catalytic alternative for construction of quaternary carbon centers. Glucoamylase from Aspergillus niger (AnGA) catalyzed the bis-Michael addition of (1E,4E)-1,5-diarylpenta-1,4-dien-3-ones with active methylene compounds to form various highly substituted trans-cyclohexanones with a quaternary carbon center.