Dinuclear zinc catalyzed asymmetric [3+2] spiroannulation for the synthesis of diverse bispirocyclic saccharines

An atom-economical asymmetric [3 + 2] spiroannulation reaction of saccharine-derived cyclic 1-azadienes with alpha-hydroxy-1-indanones has been developed via bimetallic cooperative catalysis. The developed synthesis strategy achieved through the Michael/O-Mannich cascade process allows the highly enantioselective formation of novel and diverse bispirocyclic products, in which the biologically active indanone, tetrahydrofuran, and saccharine moieties are embedded. It is noteworthy that such a protocol represents the first example of the synthesis of bispirocyclic saccharines, which will provide some support for the enrichment of chiral heterocyclic compound databases with new bioactive molecules.