Deprotection Reagents in Fmoc Solid Phase Peptide Synthesis: Moving Away from Piperidine?

Luna, Omar; Gómez, Jorge Enrique; Cárdenas, Constanza; Alberício, Fernando; Marshall, Sergio H.; Guzmán, Fanny

doi:10.3390/molecules21111542

Cited by 74 publications

(53 citation statements)

References 23 publications

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“…Fmoc group during synthesis is usually removed in a weak basic conditions, in 20% of piperidine in DMF. The reaction mechanism of Fmoc cleavage from solid support presented in Scheme 2 in the first step is based on β-elimination [ 68 ]. Initially, the proton from the fluorenyl group at the 9-position is removed by piperidine with the formation of dibenzofulvene Scheme 2 .…”

Section: Resultsmentioning

confidence: 99%

Efficient Method for the Concentration Determination of Fmoc Groups Incorporated in the Core-Shell Materials by Fmoc–Glycine

et al. 2020

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In this paper, we described the synthesis procedure of TiO2@SiO2 core-shell modified with 3-(aminopropyl)trimethoxysilane (APTMS). The chemical attachment of Fmoc–glycine (Fmoc–Gly–OH) at the surface of the core-shell structure was performed to determine the amount of active amino groups on the basis of the amount of Fmoc group calculation. We characterized nanostructures using various methods: transmission electron microscope (TEM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) to confirm the modification effectiveness. The ultraviolet-visible spectroscopy (UV-vis) measurement was adopted for the quantitative determination of amino groups present on the TiO2@SiO2 core-shell surface by determination of Fmoc substitution. The nanomaterials were functionalized by Fmoc–Gly–OH and then the fluorenylmethyloxycarbonyl (Fmoc) group was cleaved using 20% (v/v) solution of piperidine in DMF. This reaction led to the formation of a dibenzofulvene–piperidine adduct enabling the estimation of free Fmoc groups by measurement the maximum absorption at 289 and 301 nm using UV-vis spectroscopy. The calculations of Fmoc loading on core-shell materials was performed using different molar absorption coefficient: 5800 and 6089 dm3 × mol−1 × cm−1 for λ = 289 nm and both 7800 and 8021 dm3 × mol−1 × cm−1 for λ = 301 nm. The obtained results indicate that amount of Fmoc groups present on TiO2@SiO2–(CH2)3–NH2 was calculated at 6 to 9 µmol/g. Furthermore, all measurements were compared with Fmoc–Gly–OH used as the model sample.

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Section: Resultsmentioning

confidence: 99%

Efficient Method for the Concentration Determination of Fmoc Groups Incorporated in the Core-Shell Materials by Fmoc–Glycine

et al. 2020

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“…In this case, use of acidic conditions are thus required, as exemplified with Knoevenagel reactions carried out in acetic anhydride. When basic conditions are employed, piperidine is without contest one of the most popular bases due to its relatively high pKa (11.1, 25°C) which is sufficient to deprotonate activated methylene groups, its low cost, its low toxicity and easiness to evaporate [20]. However, to prepare dyes, the selection of the reaction conditions is of crucial importance as the amine can further react with the newly prepared dye, giving rise to the formation of side-products.…”

Section: Introductionmentioning

confidence: 99%

New push-pull dyes based on 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile: An amine-directed synthesis

et al. 2020

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A series of twelve dyes have been designed using 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile as the electron acceptor. While using piperidine as a classical base for the Knoevenagel reaction, a nucleophilic attack of the amine on the formed push-pull chromophore occurred, producing an azafluorenone derivative. By varying the amine, a series of azafluorenones could be obtained. By using an aldehyde of extended conjugation, a spontaneous aromatization following the cyclization reaction could also be demonstrated. The optical, electrochemical properties of the different dyes were examined. Theoretical calculations were also carried out to support the experimental results.

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“…Also, there is a limitation of piperidine availability in some institutions or countries due to use of piperidine as a substrate for illegal psychotropic drugs. This fact can cause administrative problems for purchasing piperidine 34 …”

Section: Resultsmentioning

confidence: 99%

Greener and practical synthesis of 4,4′‐(arylmethylene)bis(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ol)s through a conventional heating and a mechanochemical procedure

Khaligh

Mihankhah

2020

Journal of Heterocyclic Chem

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A new catalytic application of 4,4′‐trimethylenedipiperidine for the efficient synthesis of 4,4′‐(arylmethylene)bis(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ol)s is developed. According to the principles of green chemistry, the reaction was performed by conventional and non‐conventional processes: (a) in the refluxing ethanol using a catalytic amount of organocatalyst; (b) at room temperature in the presence of organocatalyst in a planetary ball mill under solvent‐free conditions. The organocatalyst could be reused up to 10 runs, and a negligible reduction of catalytic activity was detected. A variety of substituted 4,4′‐(arylmethylene)bis(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ol)s were obtained in good–to‐excellent yields under eco‐friendly conditions. 4,4′‐Trimethylenedipiperidine is commercially available and easy to handle and storage, less toxic, non‐flammable, as well as it shows high thermal stability and good solubility in water. The current methodology has merits including (a) wide substrate‐scope and high yields of the desired products in the short reaction times, (b) avoiding the use of hazardous solvents and acidic and metal‐containing catalysts, (c) minimize the generation of hazardous waste, and (d) simple workup process. Based on great potential as a promising organocatalyst, we hope it can be used as a greener alternative to piperidine for other organic transformations.

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Deprotection Reagents in Fmoc Solid Phase Peptide Synthesis: Moving Away from Piperidine?

Cited by 74 publications

References 23 publications

Efficient Method for the Concentration Determination of Fmoc Groups Incorporated in the Core-Shell Materials by Fmoc–Glycine

Efficient Method for the Concentration Determination of Fmoc Groups Incorporated in the Core-Shell Materials by Fmoc–Glycine

New push-pull dyes based on 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile: An amine-directed synthesis

Greener and practical synthesis of 4,4′‐(arylmethylene)bis(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ol)s through a conventional heating and a mechanochemical procedure

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