cis-Apa: A Practical Linker for the Microwave-Assisted Preparation of Cyclic Pseudopeptides via RCM Cyclative Cleavage

Abstract

A new linker cis-5-aminopent-3-enoic acid (cis-Apa) was prepared for the synthesis of cyclic pseudopeptides by cyclization-cleavage by using ring-closing methatesis (RCM). We developed a new synthetic pathway for the preparation of the cis-Apa linker that was tested in the cyclization-cleavage process of different RGD peptide sequences. Different macrocyclic peptidomimetics were prepared by using this integrated microwave-assisted method, showing that the readily available cis-Apa amino acid is well adapted as a linker in the cyclization-cleavage process.

Caferana seeds (Bunchosia glandulifera) as a new source of nutrients: Evaluation of the proximal composition, solvent extraction, bioactive compounds, and δ-lactam isolation

“…Analysis was carried out in an NMR Spectrometer in which the compound was solubilized in deuterated chloroform (CDCl 3 ). Signals obtained in the hydrogen spectrum are in line with those reported in the literature by Assaf et al, 2014 , Baron et al, 2011 who obtained synthetic δ-lactam 1 . Signals between 0 and 2 ppm refer to impurities.…”

“…The melting point (MP) of the δ-lactam 1 resulted in MP = (105.2 ± 0.8) °C. Baron et al (2011) determined the MP of the synthetic δ-lactam 1 and recorded values between 103 and 104 °C, very close to the MP attained in this work. Differences may be related to the purity of the compound isolated in this work or to the equipment accuracy.…”

Hexahydro-1H-Isoindolinone-Like Scaffolds from Electronically Deactivated and Sterically Hindered Dienes: Synthesis in the Context­ of Muironolide A

“…Coupling of but-3-enoic acid 31 and allylamine with EDCI•HCl gave β,γ-unsaturated amide 32. 24 While Boc-protection was realized, conversion to the α-diazo-β,γ-unsaturated amide 34 was unsuccessful. A small quantity of isomerized by-product (i.e., α,β-unsaturated amide corresponding to 33, not shown) was observed.…”

Metathesis Reactions on Solid-Phase: Towards New Synthesis Challenges

“…In this case the Petasis olefination and a RCM reaction was utilized as key steps. A convenient sequential on-resin RCM approach has also be used for the synthesis of a carbocyclic lantibiotic peptide [35], the synthesis of a new peptidomimetic alkene-structure (a dipeptidosulfonamide isostere) described by Liskamp and co-authors [36] on solid phase via a olefin CM reaction, the RCM reaction for the synthesis of b3-peptides [37], synthesis of analogues to Dynorphin A-peptides [38], and preparation of histone deacetylase inhibitors [39], cyclic peptoids [40], cyclic pseudopeptides [41], cyclic 11-and 10-mer peptide derivatives [42], glycopeptoids [43], lipophilic tetrapeptides [44], and peptide thioureas and triazole-containing macrocycles [45]. The CM reaction has nevertheless also been used for the preparation of many simple organic molecules and heterocycles (Fig.…”