title: A straightforward approach towards cyclic peptides via ring-closing metathesis--scope and limitations.
abstract: N- and C-terminal diallylated peptides are obtained by several approaches, such as peptide Claisen rearrangement, N- and O- allylation, and the Ugi reaction of allyl-protected components. These diallylated peptides are suitable substrates for ring-closing metathesis and the success of this cyclisation was investigated with respect to the ring size, the position of the allyl moieties and the reaction parameters. In general, excellent yields are obtained for cyclisation of allyl glycine subunits and N-allylated amides, while allyl esters and allyl carbamates often presented serious problems. However, yields of up to 73% were obtained under optimised conditions, and the new generated double bond is formed with excellent trans-selectivity.
authors.affiliation: Institut für Organische Chemie, Universität des Saarlandes, Saarbrücken, D-66123, Germany. u.kazmaier@mx.uni-saarland.de
authors.forename: Uli
authors.initials: U
authors.lastname: Kazmaier
authors.forename: Christina
authors.initials: C
authors.lastname: Hebach
authors.forename: Anja
authors.initials: A
authors.lastname: Watzke
authors.forename: Sabine
authors.initials: S
authors.lastname: Maier
authors.forename: Heike
authors.initials: H
authors.lastname: Mues
authors.forename: Volker
authors.initials: V
authors.lastname: Huch
mesh_terms: D002384:Catalysis; D003500:Cyclization; D009942:Organometallic Compounds / Q000737:chemistry; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry; D011487:Protein Conformation; D012428:Ruthenium / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D009942:Organometallic Compounds; D010456:Peptides, Cyclic; D012428:Ruthenium