Hetero-allylic asymmetric alkylation

The same catalyst system works well in hetero-allylic asymmetric alkylations (h-AAA Scheme 1-16). Substrates such as enol esters 163 provide entry to nonracemic esters of allylic alcohols. Remarkably, competing 1,2-addition and/or acyl transfer were not issues yields are good (80-99%). In these cases, catalyst loading can go as low as 0.8%, and ee s are mostly >95%. Additional chemoselectivity has been noted in the case of cinnamyl ester 163, where the desired Sn2 AAA takes place without competing Cu-catalyzed 1,4-addition to the enoate. This sets the stage for a subsequent metathesis (GH-2 = Grubbs-Hoveyda second-generation catalyst) en route to butenolide 164. 

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