Diastereoselective Aza-Claisen Rearrangement: Functional Group Assistance

Significance

Enantioselective variants of the Overman reaction are known and useful to prepare chiral building blocks (Org. Synth. 2005, 82, 134-139). However, catalytic reactions where the chirality source originates from the substrate are still very useful. The method is particularly suited for the formation of anti-1,2-hydroxylamines at the later stages in a total synthesis context. The variety of methods leading to allylic alcohols with good stereocontrol make this an attractive approach. The total syntheses of α-conhydrine and its pyrrolidine analogue were achieved in 15 and 13 steps, respectively.