Efficient asymmetric synthesis of trifluoromethylated β-aminophosphonates and their incorporation into dipeptides

Addition of anions derived from dialkyl methylphosphonates to (Ss)-N-tert-butanesulfinyl (3,3,3)-trifluoroacetaldimine afforded (Ss, R) addition adducts in moderate to good yield (53-75%) with excellent diastereoselectivity (94-95% de). After selective removal of the N-sulfinyl group, dipeptides containing enantiomerically pure diethyl 2-amino-3,3,3-trifluoropropylphosphonate were synthesized to investigate the influence of the trifluoromethyl substituent on N-terminal coupling.