1. Organic Salts and Merrifield Resin Supported [PM12O40]3- (M = Mo or W) as Catalysts for Adipic Acid Synthesis
Jana Pisk, Dominique Agustin, Rinaldo Poli Molecules. 2019 Feb 21;24(4):783. doi: 10.3390/molecules24040783.
Adipic acid (AA) was obtained by catalyzed oxidation of cyclohexene, epoxycyclohexane, or cyclohexanediol under organic solvent-free conditions using aqueous hydrogen peroxide (30%) as an oxidizing agent and molybdenum- or tungsten-based Keggin polyoxometalates (POMs) surrounded by organic cations or ionically supported on functionalized Merrifield resins. Operating under these environmentally friendly, greener conditions and with low catalyst loading (0.025% for the molecular salts and 0.001⁻0.007% for the supported POMs), AA could be produced in interesting yields.
2. Traceless solid-phase synthesis and β-turn propensity of 1,3-thiazole-based peptidomimetics
Aizhan Abdildinova, Young-Dae Gong RSC Adv. 2021 Jan 4;11(2):1050-1056. doi: 10.1039/d0ra10127c. eCollection 2020 Dec 24.
The design and solid-phase synthesis of 1,3-thiazole-based peptidomimetic molecules is described. The solid-phase synthesis was based on the utilization of a traceless linker strategy. The synthesis starts from the conversion of chloromethyl polystyrene resin to the resin with a sulfur linker unit. The key intermediate 4-amino-thiazole-5-carboxylic acid resin is prepared in three steps from Merrifield resin. The amide coupling proceeded at the C4 and C5 positions via an Fmoc solid-phase peptide synthesis strategy. After cleavage, the final compounds were obtained in moderate yields (average 9%, 11-step overall yields) with high purities (≥87%). Geometric measurements of Cα distances and dihedral angles along with an rmsd of 0.5434 for attachment with Cα of the β-turn template suggest type IV β-turn structural motifs. Additionally, the physicochemical properties of the molecules have been evaluated.
3. Compatibility study of Merrifield linker in Fmoc strategy peptide synthesis
Xiaoxiao Yang, Hao Lin, Wen Lu, Dexin Wang Protein Pept Lett. 2013 Feb;20(2):140-5. doi: 10.2174/092986613804725343.
The stability of Merrifield linker in Fmoc deprotection process was quantitatively investigated by establishing working curve of two major decomposition components from two resin bound dipeptide models. By sampling reaction solution and analyzing with RP-HPLC, decomposition rate was determined. The results indicated that either α-amino acid or β-amino acid anchored Merrifield linker was endurable for Fmoc strategy peptide synthesis in common de-Fmoc conditions such as 20% piperidine/DMF and 2% DBU/2% piperidine/DMF under room temperature treatments. However, Fmoc-deprotection with microwave assistance of α-amino acid anchored peptide resin with 20% piperidine/DMF more than 20 times or β-amino acid anchored peptide resin with 2% DBU/2% piperidine/DMF more than 30 times is not recommended. Feasibility of the proposed compatibility was verified by design and synthesis of a thymic humoral factor derived peptide via Fmoc strategy on Merrifield resin. Thus by choosing moderate de-Fmoc protocol, Merrifield resin is feasible for Fmoc strategy oligopeptide synthesis.
