Chemo- and Diastereoselective Michael–Michael-Acetalization Cascade for the Synthesis of 1,3-Indandione-Fused Spiro[4.5]decan Scaffolds

A novel, organobase-catalyzed
and highly chemoselective Michael–Michael-acetalization
cascade is presented for the efficient synthesis of spiro-indandione
skeletons. Following this very simple protocol, a broad range of products
was obtained in good yields with excellent diastereocontrol. The role
of steric factors in the acetalization step was evaluated.