[Zurück]


Vorträge und Posterpräsentationen (mit Tagungsband-Eintrag):

M. Draskovits, H. Kalaus, C. Stanetty, M.D. Mihovilovic:
"N-Heterocylic Carbene Controlled Divergent Dehomologation of Aldoses";
Poster: 21st European Symposium on Organic Chemistry, Wien; 14.07.2019 - 18.07.2019; in: "Book of Abstract", (2019), S. 143.



Kurzfassung englisch:
Despite being Nature´s biggest chiral pool, there is only a small set of standard
carbohydrates, which are readily available (commercially and synthetically). In our
research, we focus on the development of new synthetic methodology for the
interconversion of abundant sugars to more exotic ones by utilizing the natural reactivity
of the aldehyde moiety. Herein, we report our first breakthroughs in the organocatalytic
anomeric activation with N-Heterocyclic Carbenes (NHCs, as highly aldehyde selective
reagents) yielding defined dehomologation products.Inspired by the reported use of sugars as sacrificial feedstock generating multiple C1-
synthons under the mediation of NHCs [1], we have changed perspective and focused on
the sugar-based starting materials. Subjecting partially protected aldoses to the activation
we delivered a proof of concept for the feasibility of a controlled dehomologation
methodology when discovering examples of strong substrate control over the selectivity
between the initially targeted pure dehomologation and a competing follow-up reaction -
the NHC-triggered redox-lactonization (Figure 1, top).[2] Aiming for a general solution,
we targeted catalyst control over this type of divergence as ultimate goal. To facilitate the
required evaluation of changes in reaction parameters as well as catalyst structure we
developed a high throughput screening based on solid phase extraction, derivatization of
sugar compounds and quantification via calibrated GC. This survey, lead to the aspired
discovery of two types of catalysts giving either pure dehomologation or alternatively the
subsequent redox-lactonization under otherwise identical conditions (Figure 1, bottom).[3]
We hope to have set the base for future applications studied by us and others based on
NHC-catalysis under the specific and challenging conditions of reducing sugars as
reaction partners.


Elektronische Version der Publikation:
https://publik.tuwien.ac.at/files/publik_284322.pdf



Zugeordnete Projekte:
Projektleitung Christian Stanetty:
Kontrollierter Zuckerabbau durch N-Heterocyclische Carbene


Erstellt aus der Publikationsdatenbank der Technischen Universität Wien.