Enantiopure Trifluoromethylated β3,3-Amino Acids: Synthesis by Asymmetric Reformatsky Reaction with Stable Analogues of Trifluoromethyl N-tert-Butanesulfinylketoimines and Incorporation into α/β-Peptides

Addition of a Reformatsky reagent to α-aryl­(alkyl) α-trifluoromethyl N-tert-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 N-tert-butanesulfinyl β3,3-amino esters were further utilized as versatile intermediates for the elaboration of heterodi- and -tripeptides.