RESUMO
A catalytic enantioselective polycyclization of tertiary enamides with terminal silyl enol ethers has been developed by virtue of Cu(OTf)2 catalysis with a novel spiropyrroline-derived oxazole (SPDO) ligand. This tandem reaction offers an effective approach to assemble bicyclic and tricyclic N-heterocycles bearing both aza- and oxa-quaternary stereogenic centers, which are primal subunits in a range of natural alkaloids. Strategic application of this methodology and a late-stage radical cyclization as key steps have been showcased in the concise total synthesis of (-)-cephalocyclidin A.
RESUMO
We developed a simple method to fabricate a strongly coupled Fe-doped NiS2/MoS2 composite by introducing dual confinement effects during the vapor vulcanization of precursors, which involves the controlled release of metal species and the in situ formation of an N-doped carbon layer. The Fe-doped NiS2/MoS2 composite exhibited a much-enhanced hydrogen/oxygen evolution reaction performance.