Tryptophan, ruthenium complex

In their green catalytic method for the C—H alkylation of alkenes with alcohols, Yi and co-workers employed ruthenium complex 114 to alkylate Af-methylindole (113) in almost quantitative yields (116-117) whilst only generating water as the by-product (Scheme 10.38). Mechanistic experiments led the authors to propose a cationic Ru-indole-alkyl intermediate (115) that would arise from C2—H activation the exact mechanism of the C—O cleavage step is unknown. A related example with A-methoxycarbonyl-L-tryptophan methyl ester demonstrated that an indole protecting group was not necessary. 

Recently, organometallic ruthenium chemistry has found its way into biological applications. Treating [Cp Ru(MeCN)3][CF3S03] with amino acids in THF yields -coordlnated amino acid complexes of the type [Cp Ru(jj -Haa0H)][CF3S03], where HaaOH = L-HPheOH (phenylalanine) or L-HTrpOH (tryptophan), as shown in equation (24). Similarly, dipeptide and cyclopeptide complexes can be synthesized under parallel conditions. These types of complexes are essentially Cp Ru labeled peptides, which could have a notable impact on the analysis of protein receptor sites. ... 

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