Literatura académica sobre el tema "On-resin CuAAC"

Aim and Objective: The aim of our work is to demonstrate catalytic application of our previously reported simple Cu(I) ion supported on weakly acidic polyacrylate resin for Azide-Alkyne cycloaddition (CuAAC), Azide-Nitrile cycloaddition and in synthesis of 1-azido-4-methoxybenzene. Material and Method: To investigate the catalytic ability of title Cu(I) catalyst we performed the reaction of different aryl azide with a broader spectrum of different terminal alkyne and nitrile compounds. Results: The title supported Cu(I) catalyzes cycloaddition reactions of aryl azide with aliphatic, aromatic, and heterocyclic terminal alkynes and corresponding 1,4-disubstituted 1,2,3-triazoles were obtained almost in the quantitative yields. The cycloaddition reactions of aryl azide with nitriles consisting α-hydrogen on carbon attached to cyano group under catalytic action of the title supported Cu(I) ended up with the formation of 1,4- disubstituted 1,2,3-triazol-5-amines in quantitative yields. The title catalyst found to be active for nucleophilic substitution of aide group (-N3) to 4-Iodoanisole. Conclusion: It was found that both studied Azide-Alkyne cycloaddition and Azide-Nitrile cycloaddition syntheses are regioselective and quantitative in yield. The title catalyst used is economical, easily preparable, separable, and recyclable. Therefore, the studied syntheses may be regarded as environmentally clean and green processes.

The Resistance of Pine Resin and Surian Wood Sawdust Impregnated Oil Palm Stem Against Termite and WeatheringAbstractImpregnation substances into the oil palm trunks are one way to improve the oil palm trunk quality. This paper studies the optimum formulation of oil palm trunk impregnanted pine resin and Surian sawdust against dry-wood and subterranean termites as well as weathering performance. Impregnant concentration variations were mixtures of Tusam resin and Surian wood sawdust of 0% (RS0), 4% (RS1), 6% (RS2), and 8% (RS3) with three replications. Dry-wood termite test, subterranean termite test, and weather resistance test were carried out for 12 weeks of observation. The results showed that RS3 treatments were the optimum formulation of impregnated material used for oil palm trunk based on its resistance against dry-wood and subterranean termites resistance, while RS0 treatments were the optimum formula for weathering performances.Keywords: impregnation, oil palm trunk, pine resin, sawdust, Surian woodAbstrakSalah satu upaya untuk meningkatkan kualitas batang kelapa sawit adalah melalui impregnasi dengan resin pinus dan serbuk kayu Surian. Penelitian ini bertujuan untuk menentukan formulasi optimum impregnan batang kelapa sawit terhadap serangan rayap kayu kering dan rayap tanah serta ketahanan terhadap cuaca. Variasi konsentrasi impregnan yang digunakan yaitu campuran resin pinus dan serbuk kayu Surian 0% (RS0), 4% (RS1), 6% (RS2), dan 8% (RS3). Uji ketahanan rayap kayu kering, uji rayap tanah, dan uji ketahanan terhadap cuaca dilakukan selama 12 minggu pengamatan. Hasil penelitian menunjukkan bahwa konsentrasi optimum bahan impregnan batang kelapa sawit terimpregnasi terhadap ketahanan rayap kayu kering dan rayap tanah adalah formula RS3, sedangkan formulasi impregnan ketahanan cuaca optimum adalah batang kelapa sawit dengan formula RS0.Kata kunci: impregnasi, batang kelapa sawit, resin pinus, serbuk kayu, kayu Surian

5-hydroxymethylated derivatives of pyrimidine nucleosides are an important class of biologically relevant compounds. In addition, such derivatives and related compounds can be functionalized for various applications. To enable fast, economical and efficient access to 5-hydroxymethylated derivatives of 2’-deoxyuridine, we report a method of O-5 chemoselective transformation of unprotected 5-hydroxymethyl-2’-deoxyuridine (5hmdU) relying on selective etherification in the presence of alcohol promoted by the acidic Amberlyst 15 resin at room temperature. These mild conditions constitute a significant improvement compared with the harsh conditions previously described. Applied to various primary or secondary alcohols, the reaction showed a broad substrate scope, and 24 C-5 modified derivatives of 5hmdU were synthesized with good isolated yields. Notably, this efficient procedure represents a straightforward method to prepare i) several useful building blocks for subsequent chemical ligation by using CuAAC reactions, ii) natural hypermodified thymidines and analogues including glycosylated derivatives, iii) the cyanoethyl protected 5hmdU useful for solid-phase oligonucleotide synthesis.

As a key cytokine mediator of inflammation, interleukin-1β (IL-1β) binds to the IL-1 receptor (IL-1R) and activates various downstream signaling mediators, including NF-κB, which is required for immune vigilance and cellular protection. Toward the development of IL-1-targeting therapeutics which exhibit functional selectivity, the all-D-amino acid peptide 1 (101.10, H-D-Arg-D-Tyr-D-Thr-D-Val-D-Glu-D-Leu-D-Ala-NH2) was conceived as an allosteric IL-1R modulator that conserves NF-κB signaling while inhibiting other IL-1-activated pathways. Employing β-hydroxy-α-amino-γ-lactam (Hgl) stereoisomers to study the conformation about the Thr3 residue in 1, [(3R,4S)-Hgl3]-1 (2b), among all possible diastereomers, was found to exhibit identical in vitro and in vivo activity as the parent peptide and superior activity to the α-amino-γ-lactam (Agl) counterpart. Noting the relevance of the β-hydroxyl substituent and configuration for the activity of (3R,4S)-2b, fifteen different β-substituted-Agl3 analogs of 1 (e.g., 2c-q) have now been synthesized by a combination of solution- and solid-phase methods employing N-Fmoc-β-substituted-Agl3-Val-OH dipeptide building blocks. Introduction of a β-azido-Agl3 residue into the resin bound peptide and subsequent reduction and CuAAC chemistry gave access to a series of amine and triazole derivatives (e.g., 2h-q). β-Substituted-[Agl3]-1 analogs 2c-q exhibited generally similar circular dichroism (CD) spectra as that of Hgl analog 2b in water, presenting curve shapes indicative of β-turn structures. The relevance of the β-substituent was indicated in rodent models of preterm labor and retinopathy of prematurity (ROP), in which certain analogs inhibited preterm birth and vaso-obliteration, respectively, with activity similar to 1 and 2b. The β-substituted-[Agl3]-1 analogs exhibited functional selectivity on IL-1-induced signaling pathways. The described solid-phase method has provided discerning probes for exploring peptide structure-activity relationships and valuable leads for developing prototypes to treat inflammatory events leading to prematurity and retinopathy of prematurity, which are leading causes of infant morbidity and blindness respectively.

In the framework of the PhD project of industrial interest, I have been involved in the development and optimization of synthetic procedures to obtain peptides of pharmaceutical interest, both on the laboratory scale and for the industrial production, in the context of the University-Industry Joint Laboratory PeptFarm of the University of Florence. This research develops through two parallel lines. The former is related to the development of a multigram, scalable cGMP-compliant MW-SP synthetic approach for the manufacture of the cyclic peptide Active Pharmaceutical Ingredient Eptifibatide acetate. Additionally, an alternative, patentable synthetic approach has been developed to overcome patent restrictions. On the other hand, the development of an efficient synthetic strategy for the preparation of a library of stapled peptides of pre-clinical interest derived from relaxin hormone was performed, aiming to investigate their biological role. Moreover, the feasibility of an oral administration of serelaxin gastroprotected formulations were investigated. According to the industrial perspective on research needs and opportunities in manufacturing, automation of as many steps as possible within an industrial production frame is pivotal to guarantee safety requirements. Solid-phase strategies are considered methods of election for medium-length peptide syntheses not only at the research scale but for large-scale production, as well. The possibility to use microwave-assisted technology on the large scale recently introduced, prompted us to evaluate the possibility to conveniently set-up a safe and fully cGMP-compliant pilot process to produce Eptifibatide acetate Active Pharmaceutical Ingredients (API), a generic hexapeptide, characterized by a single disulfide bridge. We investigated strategies based on the use of the microwave-assisted solid-phase peptide synthesis (MW-SPPS), by the use of a DIC/Oxyma Pure coupling protocol at 90 °C. This fully automated technology, previously accessible only at R&D level, has been recently made available also for the large-scale manufacturing of peptide APIs, taking constantly into account 6 the cost-effectiveness and dangerousness of each procedure. Accordingly, we developed an optimized process at the laboratory scale (1-5 mmol), which was subsequently successfully scaled-up to 70 mmol, obtaining all the information required by regulatory agencies to validate the process and qualify the pilot-scale plant. The process consists of 5 steps: 1) automated microwave-assisted solid phase synthesis of Eptifibatide linear precursor; 2) cleavage from the resin with concomitant amino acid side-chains deprotection; 3) disulfide-bond formation in solution; 4) purification by flash column chromatography; 5) ion-exchange solid phase extraction. Since the direct scale-up of a kg-scale, cGMP compliant peptide API production procedure is a challenge that requires an accurate understanding of each involved step, we preliminary performed a quality management risk assessment, which enabled a smooth and effective achievement of a successful final result. Moreover, in our optimization process, a reduction in time, solvents and waste have been obtained, ensuring compliance with the quality specifications, according to regulatory agencies requirements (FDA and EMA). Satisfactory results were obtained in terms of Eptifibatide acetate HPLC purity (99.6%) and Yield (22.1%). Additionally, the investigation of an alternative on-resin cyclization strategy for therapeutic peptide industrial production of Eptifibatide acetate has been carried out in parallel with the aim to develop a robust and economically competitive production process avoiding intermediate steps of isolation to preserve the recovery guaranteeing a GMPs quality product, to overcome patent restrictions. A scalable, fully automated approach performed entirely in the same reactor has been developed. We explored and compared four solid-phase disulfide formation approaches (A, B, C, D) between the C-terminal Cys and the N-terminal 3- Mercaptopropionic acid (MPA). These mainly differ one from each other for the final cyclization step, obtained by direct formation of an S-S disulfide bridge (strategies A-B) or via side-chain-to-tail amide bond formation (strategies C-D). Strategy D resulted the best one, thanks to the concomitant reduction of the Stert- butylthio (StBu) Cys protecting group (PG) and disulfide formation with the MPA reducing agent, enjoying the advantage of using an already qualified starting material. This strategy (D) represents an inventive (non-obvious) 7 strategy, (since we were the first to propose MPA to deprotect StBu on cysteine), which proposes for the first time to perform all the processes including disulfide bond formation in a single reactor (novelty), scalable on multigram-scale by Liberty Pro synthesizer (Industrial applicability). Therefore, according to the three patentability criteria required for a new production process: Novelty; inventive and industrial applicability, the present PhD work identifies a new patentable production process.1 In line with the synthesis of conformationally constraint relaxin derivatives, the present work describes the development of an innovative, efficient and reproducible MW-assisted Copper-Catalyzed Azide-Alkyne Cycloaddition (SP MW-CuAAC) performed on solid phase to prepare side-chain-to-side-chain clicked H1-relaxin single B-chain analogues, overcoming the several synthetic drawbacks (aggregation tendency and poor solubility) which hamper relaxins syntheses. All the relevant parameters, that are, resin (PEG-PS vs PS), solvent mixtures (H2O:t-BuOH:DCM 1:1:1, DMSO:DMF 1:2), catalytic system (CuBr vs CuSO4), microwave energy and reaction time were optimized using a systematic approach.2 Two generations of H1-relaxin single B-chain stapled analogues were obtained. First-generation (VR and VIR) and second-generation H1-relaxin single B-chain peptides (VII and VIIR; VIII and VIIIR; IX and IXR) were characterized by different lengths and different positions and orientations of the triazolyl ring, and were designed with the aim to stabilize the α-helix conformation and to expose the binding cassette motif. The α-helicity induced by the side-chain to side-chain stapling obtained was demonstrated by the circular dichroism (CD) performed both in phosphate buffer and in SDS micelle, thanks to the collaboration with Prof. A. Carotenuto (University of Naples Federico II). Moreover, in the frame of the collaboration with Prof. D. Bani (University of Florence) and Prof. A. Hossein (Institute of Neuroscience and Mental Health, University of Melbourne, Australia), H1-relaxin analogues were biologically tested, to verify binding to cells expressing the receptor RXFP1 and activity 8 through cAMP signaling pathway in HEK-293T cells stably expressing the RXFP1 receptor. Moreover, since the major challenge in the development of peptide drugs is to improve their oral bioavailability, we investigated the relative bio-potency of the intact serelaxin molecule (the recombinant form of human H2-relaxin) and the purified porcine one, in comparison with their proteolytic fragments, obtained after treatment with Simulated Intestinal Digestion Fluid (SIF). Signalling events downstream receptor activation in THP-1 human monocytic cells was measured.