title: Synthesis of 'head-to-tail' cyclized peptides on solid support using a chelating amide as new orthogonal protecting group.
abstract: The synthesis of 'head-to-tail' cyclized peptides requires orthogonal protecting groups. Herein, we report on the introduction of bis(2-pyridylmethyl)amine (Bpa) as a new protecting group for carboxylic functions in SPPS. The synthesis of the Bpa-protected aspartic acid was straightforward, and its utility was investigated under standard peptide synthesis conditions. The new protecting group was cleaved in a very mild way using Cu(OAc)2 and 2-(trimethylsilyl)ethanol as nucleophile in a microwave oven without affecting other groups. Hence, the new group is ideally suited for the synthesis of 'head-to-tail' cyclic peptides, as demonstrated for a cyclic pentapeptide and cyclic hexapeptides.
authors.affiliation: Organische Chemie, Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany.
authors.forename: Myriam
authors.initials: M
authors.lastname: Lay
authors.affiliation: Organische Chemie, Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany.
authors.forename: Willi
authors.initials: W
authors.lastname: Bannwarth
mesh_terms: D000577:Amides / Q000737:chemistry*; D001216:Asparagine / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry*; D060326:Chemistry Techniques, Synthetic; D005973:Glutamine / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry; D010456:Peptides, Cyclic / Q000138:chemical synthesis*; D011725:Pyridines / Q000737:chemistry; D060327:Solid-Phase Synthesis Techniques; D014297:Trimethylsilyl Compounds / Q000737:chemistry
chemical_list: D000577:Amides; D002614:Chelating Agents; C000599032:N,N-bis(2-pyridylmethyl)amine; D009942:Organometallic Compounds; D010456:Peptides, Cyclic; D011725:Pyridines; D014297:Trimethylsilyl Compounds; C502030:diacetato(salicylaldehyde)copper(II); D005973:Glutamine; C043885:2-(trimethylsilyl)ethanol; D001216:Asparagine
keywords: chelating amides; cyclic peptide; orthogonal protecting group; solid-phase peptide synthesis