New applications of multiply charged ionic probes as cleavable cross-linker and polymerization reagent

We have designed new cleavable cross-linkers for biomolecules containing the 2,6-bis(oxazolinyl)pyridine (pybox) lanthanum complex. These species can effectively donate multiple charges to afford cross-linker ions for target biomolecules. The cross-linkers are cleaved easily by adding water. Moreover, we were able to detect chain structures of target molecules, including biomolecules and carbon clusters, such as fullerene C₆₀, by the addition of some MS ionic probes. Cold-spray ionization mass spectrometry demonstrated the applications of multiply charged ionic probes as cleavable cross-linkers and polymerization reagents.     

Asymmetric synthesis of cyclic α-amino acid derivatives by the intramolecular reaction of magnesium carbenoid with an N-magnesio arylamine

The synthesis of pipecolic acid and homopipecolic acid derivatives was developed from ω-(2-aminophenyl)-1-chloroalkyl p-tolyl sulfoxides by treatment with i-PrMgCl. An intramolecular nucleophilic substitution reaction of a magnesium carbenoid with an N-magnesio arylamine is the key step of this reaction. Proline and pipecolic acid derivatives were also synthesized from ω-(arylamino)-1-chloroalkyl p-tolyl sulfoxides by the same chemistry. Starting from enantiomerically pure (1S,R_S)-1-chloro-3-[2-(N-methylamino)phenyl]propyl p-tolyl sulfoxide, enantiomerically pure (R)-pipecolic acid derivative was obtained. The intramolecular nucleophilic substitution reaction of the magnesium carbenoid with N-magnesio arylamine was proven to take place with inversion of the carbenoid carbon. The stereochemistry of these reactions is also discussed.