A direct catalytic asymmetric aldol reaction of α-sulfanyl lactones: Efficient synthesis of SPT inhibitors
Softly does it: The title reaction, catalyzed by a AgPF6/(R)- biphep-type ligand/DBU complex, is described (see scheme). This protocol gives efficient access to syn-configured α-sulfanyl-β-hydroxy lactones in a highly enantioselective manner. In one particular case, the sulfide group was stereospecifically replaced with a hydroxy group to afford an enantioenriched tertiary alcohol, which upon further manipulation led to a class of densely functionalized SPT inhibitors. Copyright