Formation of Peptides at Half-Sandwich Complexes Using β- and γ-Amino Acid Esters and a Facile Dipeptide Synthesis from anN,O-Glycinato Half Sandwich Complex [RuCl(NH2CH2CO2)(η6-C6Me6)

Abstract

The tripeptide ester complexes 2 and 3 are obtained from the diglycine ester complex [RuCl(N,N′-glyglyOMe-H+)(η6-C6Me6)] and the amino acid esters H2N(CH2)nCO2Me (n = 2, 3). The reaction of the N,O-glycinato complex [RuCl(NH2CH2CO2)(η6-C6Me6)] with the β-, γ- and δ-amino acid methyl esters H2N(CH2)nCO2Me (n = 2,3,4) in CH3OH and in the presence of NaOMe affords the η3-N,N′O-dipeptide complexes [Ru{H2N(CH2)nCONCH2CO2}(η6-C6Me6)] 5−7 in good yields. These complexes are also obtained in a one pot reaction from [RuCl(μ-Cl)(η6-C6Me6)]2, glycine and the amino acid ester. The formation of small peptides at the metal represents a facile procedure which does not require either a protecting/activating group or a coupling agent.