Tripeptides alkylation reaction

The synthesis of the methyl ester of (R)-4-fluoro-3-nitro-phenylalaninc, (R)-38, a key building block in the preparation of the 16-membered cyclic tripeptide ring system of teicoplanin, was reported by Rao and co-workers [47]. This target molecule 38 was synthesized by means of an asymmetric alkylation reaction in the presence of N-benzylcinchoninium bromide (80% yield), followed by hydrolysis and esterification (85% ee Scheme 3.15 Eq. 1). 

C-Alkylation has also been observed in intramolecular reactions where the O-alkylation is not favoured.76 This property has been recently exploited in a stereocontrolled intramolecular cyclization of nitronate of nitro sugar 101 (Scheme 32), that provided the novel bicyclic nitrolactone 102, a synthetic precursor of tripeptide 103, that includes the first reported polyhydroxylated cyclopentane (3-amino acid.77... 

In addition to phosphines and pyridines, N-alkylated imidazoles are also known to act as a nucleophilic catalysts in acylation reactions [1], In the approach by Miller et al. short oligopeptides incorporating N-alkylhistidine derivatives were used as enantioselective acylation catalysts [27]. The design of, e.g., the tripeptide... 

Glusker, J. P., Carrell, H. L., Berman, H. M., Gallen, B., and Peck, R. M. Alkylation of a tripeptide by a carcinogen the crystal structure of sarcosyl-glycylglycine, 9-methyl-lO-chloromethylanthracene, and their reaction product. J. Amer. Chem. Soc. 99, 595-601 (1977). 

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