Fluorenylmethoxycarbonyl-N-methylamino Acids Synthesized in a Flow Tube-in-Tube Reactor with a Liquid-Liquid Semipermeable Membrane

Both steps of the N-methylation of 9-fluorenylmethoxycarbonyl (Fmoc) amino acids were carried out in a microstructured tube-in-tube reactor equipped with a semipermeable Teflon® AF 2400 membrane as the inner tubing. In the first step, gaseous formaldehyde was passed through the inner membrane to effect the acid-catalyzed conversion of the Fmoc amino acids into the corresponding N-Fmoc oxazolidinones. In the second step, liquid–liquid transfer of trifluoroacetic acid was used for the first time in such a reactor for the reductive opening of these oxazolidinones to give Fmoc N-methylamino acids in high yields.

ChemInform Abstract: Fluorenylmethoxycarbonyl-N-methylamino Acids Synthesized in a Flow Tube-in-Tube Reactor with a Liquid-Liquid Semipermeable Membrane.

Fluorenylmethoxycarbonyl-ProtectedO-Glycosyl-N-methyl Amino Acids: Building Blocks for the Synthesis of Conformationally Tuned Glycopeptide Antigens

Peptide antibiotics often contain N-methylated amino acids. These N-methylamino components enhance the metabolic stability and strongly influence the conformational behavior of these peptide drugs. N-Methyl-O-glycosyl amino acids, in particular, threonine and serine derivatives, are unknown so far. Fmoc-protected N-methyl-O-glycosyl-threonine and -serine building blocks, including sialyl TN antigens, have been synthesized for the first time by converting the Fmoc-protected O-glycosyl amino acids or their tert-butyl esters into the corresponding oxazolidinones followed by reductive ring-opening. These new components are considered interesting for the construction of modified mucin glycopepti…