Enantiopure 2-cyano azetidines were prepared in good yields from β-amino alcohols. This synthesis is based on two important steps: (i) Wittig olefination of a transient amino aldehyde derivedfrom a N-cyanomethylated β-amino alcohol and (ii) a 4-exotet ring closure through the intramolecular Michael addition of a lithiated α-amino nitrile. The former step is stereoselective. The thus produced functionalized
azetidinic amino acids, that can be envisioned as C-4 alkyl substituted analogues of trans-2-carboxyazetidine-3-acetic acid (t-CAA) and/or conformationally constrained analogues of (R)- or (S)-glutamic acid (Glu) have been synthesized in a diastereo- and enantiomerically pure form from beta-amino alcohols through a straightforward five step sequence. The key step of this synthesis is an original anionic