Allylic alcohols via catalytic asymmetric epoxide rearrangement

Optically active allylic alcohols can be prepared via rearrangement of epox ides using chiral lithium amides, but other than for a small subset of meso -epoxides, insufficient reactivity and enantioselectivity hamper the existi ng methods. Furthermore, the chiral reagents are often required in large ex cess. This study presents a general and highly enantioselective process tha t, in addition, is based on catalytic amounts (5 mol %) of enantiopure (1S, 3R,4R)-3-(1-pyrrolidinyl)methyl-2-azabicyclo[2.2.1]heptane and lithium diis opropylamide as the stoichiometric base. The influence of structural modifi cation of the catalyst is studied in terms of activity, enantioselectivity and aggregation behavior. The utility of the process is demonstrated by its application to a variety of epoxide derivatives (greater than or equal to 94% ee for 11 out of 14 examples), including the formal syntheses of, e.g., a prostaglandin core unit, epibatidine, carbovir, faranal, and lasiol. The system is readily extended to the resolution of racemic epoxides, which al lows access to highly enantioenriched epoxides or allylic alcohols, even at conversions near 50%.