Titanium enolates from chiral N-propanoyl-1, 3-thiazolidine-2-thiones containing bulky substituents at C4 turned out to be excellent platforms to get highly stereocontrolled cross- coupling reactions with acetals. Related oxazolidinethiones also afforded good results, but the corresponding oxazolidinones resulted completely unselective for such reactions, which proves that an exocyclic CS bond is essential to attain a synthetically useful stereocontrol.
