An improved process for solid-phase synthesis of an eicosapeptide using Fmoc chemistry.

Abstract

The present invention relates to an improved, simple, environmentally benign and cost effective process for the solid-phase synthesis of linear eicosapeptide bivalirudin, H-D-Phe-Pro-Arg-Pro-Gly-Gly-Gly-Gly-Asn-Gly-Asp-Phe-Glu-Glu-Ile-Pro-Glu-Glu- Tyr-Leu-OH (I), via orthogonal Fmoc/t-Bu strategy. For example, C-terminal amino acid Fmoc-Leu-OH was linked to p-alkoxybenzyl alc.-based solid support (Wang resin). Following deprotection of Fmoc group, second amino acid, Fmoc-Tyr(Bu-t)-OH, was coupled to Leu-O-Wang resin using HBTU/NMM in presence of polar aprotic solvent. Thus, the steps of Fmoc deprotection, followed by coupling of the next Fmoc-amino acid (except N-terminal acid was Boc-D-Phe-OH) were repeated until the resin-bound eicosapeptide, Boc-D-Phe-Pro-Arg(Pbf)-Pro-(Gly)4-Asn(Trt)-Gly-Asp(OBu-t)-Phe-Glu(OBu-t)-Glu(OBu-t)-Ile-Pro-Glu(OBu-t)-Glu(OBu-t)-Tyr(Bu-t)-Leu-O-Wang resin, was obtained. Next, cleavage and deprotection of the resin-bound peptide were performed with TFA and a non-thiol scavenger to afford crude peptide I with (at least) 90% yield and 65% purity. Addnl. purifn. steps yielded I with ≥99% purity. [on SciFinder(R)]