Chiral amides, asymmetric crotylation

Asymmetric Crotylation of Axially Chiral Amides Based on this rationale, we modified our strategy in two ways (1) introduction of a more readily removable protecting group at the phenolic hydroxy... 

A further increase in the asymmetric induction is achieved by employing a chiral auxiliary with C2 symmetry636. Thus, the rearrangement of the A.O-ketene acetal, formed on the reaction of tra j-(2S,5S)-2,5-dimethyl-l-propanoylpyrrolidine (29) with ( )-crotyl alcohol, gives amide 30 with d.r. > 10 1 in 50% yield. The fluoro derivative 31 gives amides 32-35 with 33 as the major product. 

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