122903-61-1Relevant articles and documents
Nε-carbonyl> Derivatives of Tri-L-lysine and Tetra-L-lysine as Potential Intermediates in the Block Polymer Synthesis of Macromolecular Drug Conjugates
Rosowsky, Andre,Wright, Joel E.
, p. 5551 - 5558 (2007/10/02)
Tri-L-lysine and tetra-L-lysine derivatives were synthesized with Nε-carbonyl>(Nε-Teoc) protecting groups an all the lysines, or on all but the N-terminal lysine, and with Nα-(tert-butyloxycarbonyl) (Nα-Boc) or Nα-(9-fluorenylmethyloxycarbonyl) (Nα-Fmoc) groups on the N-terminal lysines.Treatment of the Boc/Teoc peptides with p-toluenesulfonic or 2,4,6-trimethylbenzenesulfonic acid led to Boc cleavage with Teoc retention only when the Teoc/Boc ratio was 1:1 or 2:1.In contrast, treatment of the Fmoc/Teoc peptides with liquid ammonia in a sealed vessel cleaved the Fmoc group without significant loss of Teoc groups even when the Fmoc/Teoc ratio was 3:1, showing that Fmoc and Teoc groups provide more selectivity than the Boc and Teoc combination.Nα-Fmoc and Nε-Teoc groups were both stable under catalytic hydrogenolysis conditions.This made it possible to prepare Nα-Fmoc-tri-L-lysine and Nα-Fmoc-tetra-L-lysine derivatives with Nε-Teoc groups on all but the N-terminal lysine and demonstrated that the triad Fmoc/Cbz/Teoc is superior to Boc/Cbz/Teoc in peptide synthesis involving the orthogonal protection strategy.