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Identifier 000456663
Title Συνδυασμός φωτοκαταλυτικών μετασχηματισμών για τη σύνθεση ετεροκυκλικών αζωτούχων ενώσεων
Alternative Title Combining photocatalytic transformations for the synthesis of heterocyclic N-containing compounds
Author Μποσβέλη, Άρτεμις Δ
Thesis advisor Βασιλικογιαννάκης, Γεώργιος
Reviewer Στρατάκης, Εμμανουήλ
Νεοχωρίτης, Κωνσταντίνος
Σμόνου, Ιουλία
Σπύρος, Απόστολος
Παυλίδης, Ιωάννης
Ελευθεριάδης, Νικόλαος
Abstract In this dissertation, three photocatalytic methodologies yielding synthetically useful heterocyclic N-containing compounds are described. A common feature of these methodologies is the use of a new strategy wherein two different photocatalysts are combined in a single synthetic operation (one pot). The main goal is the development of photocascades that rapidly transform simple and readily accessible furan substrates into polycyclic products, without the need to purify the intermediates. Another common feature is the exploitation of the green and sustainable reagent, singlet oxygen, for the preparation of the precursors. In Chapter 2, the synthesis of polycyclic alkaloid frameworks or erythrina natural products is presented. The sequence developed makes use of photocatalyzed energy transfer processes to generate singlet oxygen and set up the substrates for the second photocatalyzed reaction, wherein electron transfer generates carbon-centered radicals for cyclizations that give the final bicyclic products. The use of an innovative strategy where two different photocatalysts are combined in a single synthetic operation (one pot) is described. The first dye (methylene blue) can be deactivated (switched off) by DIPEA after its role has been completed so that a second photocatalyst ([Ir(ppy) )2 (dtbbpy)]PF)6) can take over to genetate radicals which give the final complex frameworks. Starting from essentially flat molecules, a rapid increase in molecular complexity takes place yielding three-dimensionally complex structures, such as, the erythina alkaloid Erythrosotidienone and the common intermediate for the synthesis of Erysotramidine. In Chapter 3, a new photocatalytic ring expansion reaction that transforms γ-lactams into 2-pyridones is described. The reaction is triggered upon formation of a radical and was inspired by a late-stage oxidation commonly observed in fungal metabolism. The reaction can be included in a one pot protocol combining two different photocatalysts. For the second photocatalysis, eosin or iridium can be used. The former organic dye with its lower reduction capabilities was used to cleave a C-I bond; reactivity not previously seen for this mild photocatalyst. In this study, eosin was shown to have the ability to cleave a C-I bond activated by a -OMe group beta to the iodide. In Chapter 4, the synthesis of a series of colibactin warhead model compounds is reported. These were used to provide new insight into two key mechanisms in colibactin chemistry. An explanation is provided for why the colibactin warhead sometimes undergoes a ring expansion-addition reaction sequence to give fused cyclobutyl products, while, at other times, nucleophiles add directly to the cyclopropyl unit (as when DNA adds to colibactin). Finally, some evidence that Cu(II) chelated to colibactin may catalyze an important oxidation of the colibactin-DNA adduct is provided. The Cu(I) generated as a result could then also play a role in inducing double strand breaks in DNA.
Language Greek
Subject 2-pyridones
2-πυριδόνες, κολιμπακτίνη
Alkaloid synthesis
Colibactin
Eosin
Erythrina
Furans
Methylene blue
Multi-photocatalyst cascades
One pot reaction sequences
Photocatalysis
Ring expansion
Singlet oxygen
Διαδοχικές φωτοκαταλυτικές διεργασίες
Διεργασίες μιάς φιάλης
Επέκταση δακτυλίου
Ερυθρίνα
Εωσίνη
Κολιμπακτίνη
Μπλε του μεθυλενίου
Οξυγόνο απλής κατάστασης
Σύνθεση αλκαλοειδών
Φουράνια
Φωτοκατάλυση
γ-lactams
γ-λακτάμες
Issue date 2023-07-03
Collection   School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/9/7/8/metadata-dlib-1687850309-909370-468.tkl Bookmark and Share
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