Enantioselective Total Synthesis of (-)-Hunterine A Enabled by a Desymmetrization/Rearrangement Strategy

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.

Regioselectivity in the ring opening of non-activated aziridines

In this critical review, the ring opening of non-activated 2-substituted aziridines via intermediate aziridinium salts will be dealt with. Emphasis will be put on the relationship between the observed regioselectivity and inherent structural features such as the nature of the C2 aziridine substituent and the nature of the electrophile and the nucleophile. This overview should allow chemists to gain insight into the factors governing the regioselectivity in aziridinium ring openings (81 references).