Synthesis of β and γ‐fluorenylmethyl esters of respectively Nα‐Boc‐L‐aspartic acid and Nα‐Boc‐L‐glutamic acid

FAHAD AL‐OBEIDI, DOUGLAS G. SANDERSON, VICTOR J. HRUBY

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

The orthogonal synthesis of Nx‐Boc‐L‐aspartic acid‐γ‐fluorenylmethyl ester and Nα‐Boc‐L‐glutamic acid‐δ‐fluorenylmethyl ester is reported. This is a four‐step synthesis that relies on the selective esterification of the side‐chain carboxyl groups on Nx‐CBZ‐l‐aspartic acid and Nα‐CBZ‐l‐glutamic acid. Such selectivity is accomplished by initially protecting the a‐carboxyl group through the formation of the corresponding 5‐oxo‐4‐oxazolidinone ring. Following side‐chain esterification, the α‐carboxyl and α‐amino groups are deprotected with acidolysis. Finally, the α‐amino group is reprotected with the t‐butyl‐oxycarbonyl (Boc) group. Thus aspartic acid and glutamic acid have their side‐chain carboxyl groups protected with the base‐labile fluorenylmethyl ester (OFm) and their α‐amino groups protected with the acid‐labile Boc group. These residues, when used in conjunction with Nx‐Boc‐Nε‐Fmoc‐l‐lysine, are important in the formation of side‐chain to side‐chain cyclizations, via an amide bridge, during solid‐phase peptide synthesis.

Original languageEnglish (US)
Pages (from-to)215-218
Number of pages4
JournalInternational journal of peptide and protein research
Volume35
Issue number3
DOIs
StatePublished - Mar 1990

Keywords

  • 5‐oxo‐4‐oxazolidinone ring
  • N‐Boc‐Ll‐aspartic acid‐γ‐fluorenylmethyl ester
  • N‐Boc‐l‐glutamic acid‐δ‐fluorenylmethyl ester
  • peptide cyclization
  • α‐selective protection

ASJC Scopus subject areas

  • Biochemistry

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