Synthesis of chiral amino acids with metal ion chelating side chains from l-serine using Negishi cross-coupling reaction

The scope of the Negishi cross-coupling reaction of organozinc compounds derived from chiral amino acids was extended to electron rich iodoanilines and iodobenzylamines as coupling reagents. The protocol allows the direct modification of serine into phenylalanine derivatives bearing metal ion chelating ligands in their side chain, such as amino esters 6 and 7. The preparation of metal complex labeled peptides, the construction of synthetic receptors and hybrid materials are potential applications of the modified chiral amino acids.     

Zum Forschen nach China

Michael Kruppa und Stefan Ritter haben während ihrer Doktorarbeit zwei Monate am Shanghai Institut of Organic Chemistry in China gearbeitet.     

Spin Chemistry Investigation of Peculiarities of Photoinduced Electron Transfer in Donor–Acceptor Linked System

Photoinduced intramolecular electron transfer in linked systems, (R,S)- and (S,S)-naproxen-N-methylpyrrolidine dyads, has been studied by means of spin chemistry methods [magnetic field effect and chemically induced dynamic nuclear polarization (CIDNP)]. The relative yield of the triplet state of the dyads in different magnetic field has been measured, and dependences of the high-field CIDNP of the N-methylpyrrolidine fragment on solvent polarity have been investigated. However, both (S,S)- and (R,S)-enantiomers demonstrate almost identical CIDNP effects for the entire range of polarity. It has been demonstrated that the main peculiarities of photoprocesses in this linked system are connected with the participation of singlet exciplex alongside with photoinduced intramolecular electron transfer in chromophore excited state quenching.