Synthesis of β-Benzylsulfanyl-β-trifluoromethyl-α-amino Acids Via Michael Addition in the Presence of Et3N/LiBr

β-Benzylsulfanyl-β-trifluoromethyl-α-amino acid esters have been synthesized from (Z)-β- substituted-β-trifluoromethyl-α,β-dehydroamino acid esters via Michael addition with moderate diastereoselectivities. The reaction was investigated with various catalysts. Et3N and LiBr gave satisfactory results, which operated synergistically as bifunctional catalyst. However, the other tested chiral catalysts gave no good enantioselectivities. Keywords: fluorinated amino acids, sulfur substituted amino acids, michael addition, dehydroamino acid esters, bifunctional catalyst, mercaptanes