Fluorinated beta2- and beta3-amino acids: Synthesis and inhibition of alpha-chymotrypsin

The synthesis of a series of alpha-fluorinated beta(2)- and beta(3)-amino acid derivatives is described. Stereoselective fluorination at the alpha-carbon of the beta(3)-amino acids was achieved by deprotonation with lithium diisopropylamide followed by treatment with N-fluorobenzenesulfonimide. Fluorination of beta(2)-amino acids employed the chiral auxiliary (4R)-4-benzyl-2-oxazolidinone. The alpha-fluorinated amino acids and their non-fluorinated precursors were found to competitively inhibit alpha-chymotrypsin.