A Facile Two-Step Synthesisof Novel Ring-A Double Substituted Tryptophan Building Blocks forCombinatorial Chemistry

Abstract

A fast synthesis of ring-A disubstituted Fmoc and Boc protected L-tryptophan analogs was achieved starting from the appropriate 2,4-or 2,3-disubstituted phenylhydrazines and optically active N,N-diprotected L-glutamic acid g-aldehydes, utilizing a Fischer-indole synthesis as a key step. Unlike most of the previously reported methods, that required the multistep stereoselective generation of a chiral carbon, this fast methodology is useful for generating optically active ring-A disubstituted protected tryptophans starting from a simple and common chiral precursor. These building blocks have a wide application scope in peptide and combinatorial chemistry fields.

Toward the development of a novel non-RGD cyclic peptide drug conjugate for treatment of human metastatic melanoma

“…The synthesis of the cyclic peptides was done by a previously described procedure [43–48]. Briefly, 2-chlorotrityl chloride resin (1.12 mmol/gr) was placed in a reactor and suspended in DCM under nitrogen atmosphere.…”