Stereoselective Syntheses of Masked β-Amino Acid Containing Phthalides.

We herein report a protocol for the asymmetric aldol-initiated cascade addition of isoxazolidin-5-ones to -cyanobenzaldehydes by using 's bifunctional organocatalyst. This approach allows for the synthesis of various novel β-amino acid-phthalide conjugates with good enantio- and diastereoselectivities in reasonable yields and the further ring-opening of these compounds to acyclic carboxylic acid derivatives was demonstrated too.