title: Solid-phase synthesis of MEN 11270, a new cyclic peptide kinin B2 receptor antagonist.
abstract: An efficient synthesis of the cyclic decapeptide MEN 11270 [H-DArg1-Arg2 Pro3-Hyp4-Gly5-Thi6-Dab7-DTic8-Oic9-Arg10 c(7gamma - 10alpha)] was developed. Two three-dimensional orthogonal strategies were applied and compared: Fmoc/Tos/Boc (procedure A) and Fmoc/Pmc/Dde (procedure B). Both resulted in a 23-step strategy comprising the stepwise solid-phase chain assembly of the linear protected peptide, partial deprotection, solution-phase cyclization and final full deprotection. The stepwise assembly of the linear peptide was optimized by double coupling and acylation time prolongation for critical residues (Tic, Dab, Thi, Pro). O-(7-azabenzotriazol-1-yl)-N,N,N',N' tetramethyluronium (HATU) was preferred as coupling reagent for Dab. In the cyclization step, the partial racemization of Arg10 (31% using 1-ethyl-3-(3'-dimethyl-aminopropyl) carbodiimide/1-hydroxybenzotriazole (EDC/HOBt) as activation system) was reduced to 3% with HATU. The final deprotection was performed in the presence of dimethylsulfide (procedure A) and thiocresol (procedure B) as scavengers, to avoid the sulfation of Hyp side chain. The final compound and the main by-products were characterized by mass spectroscopy (MS), nuclear magnetic resonance (NMR) and racemization test. Procedure B produced operationally simpler and more efficient results than A (28% overall yield versus 4%).
authors.affiliation: Menarini Ricerche, Florence, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Anichini
authors.forename: R
authors.initials: R
authors.lastname: Ricci
authors.forename: G
authors.initials: G
authors.lastname: Fabbri
authors.forename: G
authors.initials: G
authors.lastname: Balacco
authors.forename: S
authors.initials: S
authors.lastname: Mauro
authors.forename: A
authors.initials: A
authors.lastname: Triolo
authors.forename: M
authors.initials: M
authors.lastname: Altamura
authors.forename: C A
authors.initials: CA
authors.lastname: Maggi
authors.forename: L
authors.initials: L
authors.lastname: Quartara
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D065168:Bradykinin Receptor Antagonists; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D015394:Molecular Structure; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000494:pharmacology; D010446:Peptide Fragments / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000494:pharmacology; D043782:Receptor, Bradykinin B2; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000596:Amino Acids; D065168:Bradykinin Receptor Antagonists; C119318:MEN 11270; D009842:Oligopeptides; D010446:Peptide Fragments; D010456:Peptides, Cyclic; D043782:Receptor, Bradykinin B2