- CONTINUOUS, SOLVENT-FREE AND NON-ENZYMATIC PEPTIDE SYNTHESIS BY REACTIVE EXTRUSION
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The present disclosure relates to A a continuous, solvent-free and non-enzymatic method for synthesizing a compound of formula (I): Ra-POLYPEP-Rc (I) wherein: POLYPEP is a poly-amino acid compound, Ra and Rc are as specified in the disclosure, which method comprises the steps of: a) feeding an extrusion reactor with (1) a compound of formula (II) Ra-PEPNt-Rg (II) wherein; PEPNt is a mono- or a poly-aminoacid compound, Ra and Rg are as specified in the disclosure, and (2) a compound of formula (III) H-PEPCt-Rc (III) wherein: PEPCt is a mono- or a poly-amino acid compound, and Rc is as defined in the disclosure in the absence of any solvent, so that the compound of formula (II) and the compound of formula (III) react together for generating a compound of formula (I), and b) collecting the compound of formula (I) from the extrusion reactor.
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Page/Page column 38; 39
(2019/09/04)
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- Multistimuli-responsive supramolecular organogels formed by low-molecular-weight peptides bearing side-chain azobenzene moieties
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This work demonstrates that the incorporation of azobenzene residues into the side chain of low-molecular-weight peptides can modulate their self-assembly process in organic solvents leading to the formation of stimuli responsive physical organogels. The major driving forces for the gelation process are hydrogen bonding and π-π interactions, which can be triggered either by thermal or ultrasound external stimuli, affording materials having virtually the same properties. In addition, a predictive model for gelation of polar protic solvent was developed by using Kamlet-Taft solvent parameters and experimental data. The obtained viscoelastic materials exhibited interconnected multistimuli responsive behaviors including thermal-, photo-, chemo- and mechanical responses. All of them displayed thermoreversability with gel-to-sol transition temperatures established between 33-80 °C and gelation times from minutes to several hours. Structure-property relationship studies of a designed peptide library have demonstrated that the presence and position of the azobenzene residue can be operated as a versatile regulator to reduce the critical gelation concentration and enhance both the thermal stability and mechanical strength of the gels, as demonstrated by comparative dynamic rheology. The presence of N-Boc protecting group in the peptides showed also a remarkable effect on the formation and properties of the gels. Despite numerous examples of peptide-based gelators known in the literature, this is the first time in which low-molecular-weight peptides bearing side chain azobenzene units are used for the synthesis of "intelligent" supramolecular organogels. Compared with other approaches, this strategy is advantageous in terms of structural flexibility since it is compatible with a free, unprotected amino terminus and allows placement of the chromophore at any position of the peptide sequence. Intelligent response: The incorporation of the azobenzene moiety into the side chain of low-molecular-weight peptides allows for the preparation of multistimuli-responsive supramolecular organogels. The presence and position of the azobenzene residue act as a versatile regulator to reduce the minimum gelation concentration and enhance both the thermal stability and mechanical strength of the materials (see figure). Copyright
- Fatás, Paola,Bachl, Jürgen,Oehm, Stefan,Jiménez, Ana I.,Cativiela, Carlos,Díaz Díaz, David
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supporting information
p. 8861 - 8874
(2013/07/26)
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- Activation of carboxylic acids as their active esters by means of tert-butyl 3-(3,4-dihydrobenzotriazine-4-on)yl carbonate
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Carboxylic acids were activated in the presence of DMAP with tert-butyl carbonates (BOC-OX) 1, which were prepared in situ by reaction of X-OH and di-tert-butyl dicarbonate (BOC2O). The most efficient active carbonate proved to be tert-butyl 3-(3,4-dihydrobenzotriazine-4-on)yl carbonate 1a, leading to efficient formation of benzotriazinonyl esters 3 and 6, which are intermediates in reactions with primary and secondary amines to afford amides or peptides in good yield. By-products in the formation of 3 or 6 are the environmentally safe tert-BuOH and CO2. The hindered amino acid AIB also forms a dipeptide in good yield.
- Basel, Yochai,Hassner, Alfred
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p. 2529 - 2533
(2007/10/03)
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- The preparation of L,L-aspartame citric amide
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Mono-substituted L,L-aspartame citric amide 1 was prepared via coupling L,L-α-BMAP 3 with 1,2-dibenzyl citrate 2 prepared from selective hydrolysis of tribenzyl citrate 5.
- Katritzky, Alan R.,Fang, Yunfeng,Prakash, Indra
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p. 675 - 677
(2007/10/03)
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