α,α-Difluoro-β-lactams successfully underwent ring-opening aminolysis with various
amino acids in 2,2,2-trifluoroethanol to afford fluorine-containing peptides. In this
aminolysis, it was found that 2,2,2-trifluoroethanol first attacked the α,α-difluoro-β-lactams
with cleavage of lactam ring to form the corresponding open-chain 2,2,2-trifluoroethyl
esters as reactive intermediates. The trifluoroethyl esters were more electrophilic
compared with the corresponding methyl ester and thereby accelerated the aminolysis
with various amino acids to form β-amino acid peptides with α,α-difluoromethylene
unit.
Key words
fluorine - peptide - β-amino acid - α,α-difluoro-β-lactam - 2,2,2-trifluoroethanol
