Synthesis of Trifluoroacetamidoketones by Acylation of Ferrocene with In Situ Protected Amino Acids.

The Friedel-Crafts acylation of ferrocene with amino acids carried out under mild conditions (metal-free catalytic system, room temperature, and a short reaction time of 1 h) has been reported. The acylating agent is generated in situ by N-protection of the amino group of the amino acid, followed by formation of mixed anhydride. This one-pot triflic-acid-promoted reaction provides -trifluoroacetyl-protected amidoketones in good to excellent yields. Moreover, the trifluoroacetyl group can be easily removed or replaced with another protecting group under mild conditions in a one-pot procedure.