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A Kinetic Model for Reppe Synthesis in Dimethyl …
A) Shows the chemical structure of 4, the cRGD-peptide derivatized with tetra-[(2-aminoethyl)glycine] N-functionalized Reppe Anhydride. B) Synthetic route for the preparation of 4. The solid phase support is depicted by the grey circle. (a) condensation of the first amino acid; (b) stepwise elongation on 2-chlorotrityl resin; (c) cyclization steps: 1. Pd(PPh3)4, morpholine; 2. PyCLOCK, DIPEA; (d) conjugation to Reppe Anhydride derivative: 1. Hydrazine monohydrate; 2. Stepwise elongation, 3. Acetylation; (e) cleavage from resin and deprotection: TFA, TIS, water. C) The upper panel shows the HPLC chromatogram of the purified peptide 4. The solvent gradient was raised from 5 % to 100 % acetonitrile in 5 min (starting immediately) at a flow rate of 6 ml/min. The aqueous phase consisted of water containing 0.1 % TFA. The lower panel shows the MALDI-TOF spectrum of the purified peptide 4.
To visualize the cRGD-targeted TMZ-containing constructs, the NIR dye Cy7 was incorporated. It is interesting to note that the absorption measurements of the Cy7-tetrazine precursor 6, the reaction partner for inverse Diels-Alder (DARinv)-based click chemistry, revealed an absorption maximum of 745 nm and that this maximum shifted to approximately 800 nm after ligation to the carrier material. To what extent fluorescence resonance energy transfer effects are involved in the shift of the absorption maximum toward 800 nm remains to be clarified. Analogous NIR imaging studies with Cy7-labeled neutrophil-specific agents showed no differences in spectra between non-conjugated and peptide-conjugated Cy7 dyes . The fact that the Cy7 precursor used here is ligated to a diaryl-tetrazine, acting as a diene reaction partner for the DARinv, might explain this shift, but further experiments are required to confirm this assumption. Using capillaries and the XFM-2 phantom, which simulates the scattering and light attenuation of tissues in mice, we finally confirmed that the prepared Cy7-containing constructs are highly suited for NIR fluorescence imaging. Strong signals were observed even at a dose of 1 nM, and signal intensities linearly correlated with the concentrations of the probes. Remarkable is the fact that the use of probe II with one Cy7 as an imaging molecule (cRGD-TMZ3-Cy71) is sufficient for imaging as observed in the mouse phantom studies. The measurements of construct IV containing four Cy7 molecules (cRGD-Cy74) did not show much higher fluorescence intensities. This offers the possibility of conjugating other imaging or therapeutic probes to the versatile BioShuttle backbone, e.g. a chelator for radiometal complexation and/or an additional drug, in order to obtain multimodal theranostic formulations for simultaneously delivering multiple chemotherapeutic drugs to cancer cells. The results obtained here provide some initial experimental evidence in this direction, showing that cRGD-TMZ2-Cy72 might be a promising agent for targeted therapy combined with optical imaging of tumors. Experiments to validate these findings in living mice, as well as studies to evaluate the antitumor efficacy of these integrin-targeted theranostic agents, are planned for the near future.
Synthesis of the dienophile by the Reppe process
Both targeted therapeutics and molecular imaging agents have already been shown to be highly suitable materials for facilitating disease diagnosis and therapy. Therefore cell- and tissue-specific targeting with so-called theranostic agents, which combine diagnostic and therapeutic properties within a single formulation, are more and more considered to be one of the next major leaps forward for enabling personalized medicine [-]
Shibasaki of the University of TokyoPGE1 synthesis via a two-component coupling process:Developed by Proffessor Sato of Tokyo Institute of Technology.Synthesis of diphenylethanediamines:Metalative Reppe Reaction:Intramolecular nucleophilic acyl substitution reaction (INAS reaction):Suzuki-Miyaura coupling:Developed by Proffessor Sato of Tokyo Institute of Technology.
Arama sonuçarı "Reppe Synthesis"
Reppe, to dehydrate the butanediol to butadiene in two steps:
that is, first to tetrahydrofurane and then the latter to butadiene.
Tetrahydrofurane appears to be an important new building block in synthetic chemistry.
Using the inverse Diels-Alder reaction, several different BioShuttle-PNA constructs targeted to αvβ3 integrins and functionalised with TMZ as a therapeutic agents and with Cy7 as an imaging agent were prepared. One of these compounds, i.e cRGD-TMZ2-Cy72, showed enhanced cytotoxicity as compared to free TMZ, as well as very favourable imaging properties in NIR measurements. These results provide initial proof-of-principle for the potential of this formulation to be used as a theranostic agent. Follow-up experiments are currently underway to validate the usefulness of cRGD-TMZ2-Cy72 in tumor-bearing animals.
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Walter Reppe began his study of the natural ..
A tetracyclic anhydride, synthesized and well described by Reppe (best-known under the name of Reppe-Anhydride) turned out to be the ideal compound for our purpose 15 (Figure ). It is easily available by the classic Diels-Alder-Reaction of cyclooctatetraene (COT) 13 and maleic anhydride 14. [-] Additionally to the anhydride function this tetracyclic compound possesses a reactive double bond inside of the cyclobutene ring. The presence of a further double bond inside of the cyclohexene ring is not of relevance due to the inactivity of this double bond in the DARinv. The anhydride ring of the tetracyclic compound can be converted to the substituted corresponding imides, whereas the yield is nearly quantitative and the product can be purified easily by recrystallization (scheme/table ). Further ring systems, dedicated for chemical reactions as described above, are the cyclobutene-3,4-dicarboxylic acid anhydride [, ], as well as the commercially available and norbornen-anhydrides.
Reppe Vinylation - Comprehensive Organic Name …
Since Germany was cut off from
key raw materials such as natural rubber during World War II, butanediol was used to produce the synthetic rubber Buna.
The bombing of Ludwigshafen forced Reppe to transfer in September 1944 to the inorganic facility at Gendorf in Upper Bavaria, where he conducted olefin
high pressure experiments in a smaller laboratory.
Reppe Reaction | Article about Reppe Reaction by The …
(Scheme 4) Synthesis of a versatile building block for modification of peptides. The syntheses of the Reppe-Anhydride 15 and the corresponding Boc-Lys derivative 16 are described .
Selective Preparation of Benzyltitanium Compounds by …
Dilution of acetylene with inert nitrogen gas and the use of stainless
steel, walled reactor tubes were key discoveries in working safely with acetylene at pressures up to 200 atm.
Reppe now began to synthesize a wide variety of different vinyl compounds.
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