Die Formylgruppe als hydrogenolytisch abspaltbare Schutzgruppe für Peptidsynthesen

Abstract

Durch katalytische Hydrierung in chlorwasserstoffhaltigem Tetrahydrofuran läßt sich die Formylgruppe aus N‐Formylaminosäure‐ und ‐peptidestern quantitativ abspalten. Die Anwendbarkeit dieser Methode zum Aufbau von Peptiden aus N‐Formylaminosäuren wird nachgewiesen.

Synthetic Strategies TowardN‐Functionalized Cyclens

“…Alkaline hydrolysis of various N ‐formylcyclens was found to be ineffective by our group36 and by others,45b although the formyl group can be efficiently removed by acidic hydrolysis 45b,51. Other methodologies investigated in our laboratory, such as oxidative65b or reductive65c removal of the formyl group proved to be rather troublesome, leading either to decomposition (oxidation) or recovery of the starting material (catalytic hydrogenation) 36…”

A new synthesis of cystamine modified Eu3+ DOTAM-Gly-Phe-OH: a conjugation ready temperature sensitive MRI contrast agent

“…It is this latter manifestation of reactivity that we intend to exploit for the formation of peptidechelator complexes. Synthetic routes based on the peralkylation of easily accessible cyclen derivatives [N-formylcyclen (9), N-cyclenacetic acid (10)] permitted us to explore some new chemistry, yet did not lead to a workable synthesis of ligands 5 and their Eu 3+ complexes. Selective trialkylation of cyclen (6) with N-iodoacetyl-Gly-Phe-OEt (7) was also found to be problematic.…”

“…Another easily accessible cyclen-derived precursor investigated for the synthesis of ligand 5 was N-cyclenacetic acid (10). 7 Our approach was to trialkylate 10 (Scheme 1) with Niodoacetyl-Gly-Phe-OEt (7), followed by coupling with Fmoc-Phe-cystamine(Boc) (11, Scheme 1).…”

“…10 mL) and set aside for 18 h at −20 • C. The precipitate that formed (DCU) was removed by filtration through a cotton plug placed in a Pasteur pipette. The solvent was removed to give N-chloroacetyl-Gly-Phe-OtBu (12a, 1.734 g, 98% (10), 298 (32), 224 (25), 148 (100), 120 (100), 99 (21).…”

“…one-third of its original volume, diluted with EtOAc (50 mL) and washed with 10% Na 2 SO 3 solution (50 mL). The aqueous phase was extracted with EtOAc (30 mL), the organic phase was dried, concentrated, and the residue was subjected to FCC on 30 g SiO 2 (hexanes-acetone, 1 : 1) to afford 752 mg (56%) of N-iodoacetyl Gly-Phe-OtBu (12b (10), 120 (100), 99 (15). (8).…”