Highly diastereoselective 1,3-dipolar cycloaddition via in situ formed ketimine ylides

1,3-Dipolar cycloaddition of conjugated unsaturated ketimine ylides was disclosed. The reaction of glycine ester with a series of β,γ-unsaturated keto esters in the presence of catalytic amount of TFA was found to give structurally diverse and functionally enriched pyrrolidine derivatives 3 in up to 88% yield. These processes feature a hydrolysis of glycine ketimine. A preliminary enantioselective version of the transformation was also investigated.