RESUMO
The first enantioselective total synthesis of (-)-hunterine A is disclosed. Our strategy employs a catalytic asymmetric desymmetrization of a symmetrical diketone and subsequent Beckmann rearrangement to construct a 5,6-α-aminoketone. A convergent 1,2-addition joins a vinyl dianion nucleophile and the enantioenriched ketone. The endgame of the synthesis features an aza-Cope/Mannich reaction and azide-olefin dipolar cycloaddition to complete the pentacyclic ring system. The synthesis is completed through a regioselective aziridine ring opening.
RESUMO
An enantioselective iridium-catalyzed allylic alkylation of malonates with trisubstituted allylic electrophiles to form all-carbon quaternary stereocenters is reported. This reaction proceeds at ambient temperature and enables the preparation of a wide range of enantioenriched products in up to 93% yield and 97% ee. The quaternary products can be readily converted to several valuable building blocks such as vicinal quaternary products and ß-quaternary acids.
Assuntos
Compostos Alílicos , Alquilação , Carbono , Catálise , Malonatos , EstereoisomerismoRESUMO
The regioselective and enantioselective intermolecular sp3 C-H functionalization of silicon-substituted alkanes with aryl diazoacetates was accomplished using the recently developed dirhodium catalyst Rh2( S-TPPTTL)4. These reactions generate a diverse array of stereodefined substituted silacycloalkanes with high enantioselectivity and diastereoselectivity.