Sustainable Asymmetric Organolithium Chemistry: Enantio- and Chemoselective Acylations through Recycling of Solvent, Sparteine, and Weinreb Amine

The well-established Hoppe-Beak chemistry, which involves enantioselective generation of organolithium compounds in the presence of (-)-sparteine, was revisited and applied to unprecedented acylations with Weinreb amides to access highly enantioenriched alpha-oxyketones and cyclic alpha-aminoketones. Recycling of the sustainable solvent cyclopentyl methyl ether, sparteine, and the released Weinreb amine [HNMe(OMe)] was possible through a simple work-up procedure that enabled full recovery of these precious materials. The methodology features a robust scope and flexibility, thus allowing the enantioselective preparation of scaffolds amenable of further derivatization.