Stereoselective mannich reactions of mono thiomalonates : & screening for peptidic triazolium salt based catalysts

Part I: The stereoselective synthesis of ß-amino thioesters is of high interest since they are versatile and common building blocks for a variety of pharmaceutically important compounds. Within this thesis a mild organocatalyzed approach for the synthesis of ß-amino thioesters by using mono thiomalonates (MTMs) as thioester enolate equivalents was developed. Those nucleophiles proved to be highly reactive in Mannich reactions providing for acyclic ß2-amino thioesters and ß2,3,3-amino thioesters with adjacent tertiary and quaternary stereocenters in high yields and excellent stereoselectivities. In addition, the synthetic value of ß-amino thioesters as building blocks for coupling-agent-free liquid phase, as well as solid phase peptide synthesis was shown.
Part II: In the second part of this thesis the combinatorial approach of encoded one-bead-one-compound libraries was successfully used to identify bifunctional peptidic N-heterocyclic carbene catalysts for the redox amidation reaction of aldehydes and amines.