Enantiopure Trifluoromethylated β^3,3-Amino Acids: Synthesis by Asymmetric Reformatsky Reaction with Stable Analogues of Trifluoromethyl <i>N</i>-<i>tert</i>-Butanesulfinylketoimines and Incorporation into α/β-Peptides

Addition of a Reformatsky reagent to α-aryl­(alkyl) α-trifluoromethyl <i>N</i>-<i>tert</i>-butanesulfinyl hemiaminals, bench-stable surrogates of trifluoromethyl ketoimines, provided β-alkyl­(aryl) β-trifluoromethyl β-amino acids derivatives in good yields and high diastereoselectivities. The <i>N</i>-<i>tert</i>-butanesulfinyl β^3,3-amino esters were further utilized as versatile intermediates for the elaboration of heterodi- and -tripeptides