Deuterium and tritium exchange studies with phenylalanines and phenylglycine in the presence of homogeneous potassium tetrachloroplatinate(II) catalyst

Abstract

K2PtCl4 was found to be an efficient and very useful homogenous catalyst for deuterium and tritium exchange of the aromatic hydrogens of phenylalanines and phenylglycine. The exchange reactions of the aromatic ring hydrogens, observed in the 80–130°C temperature interval proceed according to an electrophilic substitution mechanisms. The investigated hydrogen exchange processes involve the reversible formation of π-complexes with the aromatic ring, analogous to π-complexes postulated in deuterium exchange studies with alkylbenzenes. The probable mechanisms of the platinum(II) catalyzed homogeneous deuterium and tritium exchange of aromatic ring hydrogens and of the methoxy and ethoxy para-substituents are discussed.