Asymmetric base-promoted epoxide rearrangement: achiral lithium amides revisited

The use of achiral bases other than lithium diisopropylamide (LDA) was investigated for the asymmetric (1S,3R,4R)-3-(pyrrolidinyl)methyl-2-azabicyclo[2.2.1]heptane catalyzed rearrangement of cyclohexene oxide to (1R)-cyclohex-2-en-1-ol. No significant improvement of the reaction protocol was achieved although some interesting trends were observed. The enantioselectivity in the cyclohexene oxide rearrangement was however markedly improved by slow addition of the achiral base.