Palladium(II)-Catalyzed Oxidative Cyclization Strategies: Selective Formation of New C-C and C-N Bonds
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
The main focus of this thesis has been directed towards preparation and oxidative carbocyclization of en-, dien- and aza-enallenes.
In the first part of this thesis, a stereoselective oxidative carbocyclization of dienallenes was realized. By employing cheap and readily available palladium trifluoroacetate we were able to efficiently cyclize a variety of dienallenes into hydroxylated carbocycles in high yield and high selectivity. This oxidative process was compatible with two different reoxidation protocols: one relying on p-benzoquinone (BQ) as the oxidant and the other employing molecular oxygen as the oxidant.
In the second part of the thesis the carbocyclization methodology was extended to include carbocyclization of aza-enallenes. This was achieved in two distinct steps. First, a copper-catalyzed coupling of allylic sulfonamides with bromoallenes was developed, giving access to the corresponding aza-enallenes. Subjecting these substrates to catalytic amounts of palladium acetate, along with BQ as the oxidant, rendered N-heterocycles in good yield. The reactivity of these N-heterocycles towards activated dienophiles was later exploited in a tandem (aerobic) oxidative carbocyclization/Diels-Alder reaction.
The third topic involves efficient oxidative arylative/borylative carbocyclization of enallenes. These reactions, catalyzed by palladium acetate, relies on transmetallation of a (σ-alkyl)palladium(II) intermediate with diboranes or arylboronic acids. With this novel methodology we were able to obtain an array of arylated or borylated carbocycles, as single diastereomers, in high yield.
Finally, we developed a palladium(II)-catalyzed cyclization of allylic carbamates. This mild, operationally simple, and scalable catalytic reaction opens up access to an array of oxazolidinones in high yield and excellent diastereoselectivity.
Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University , 2012. , 88 p.
Carbocyclization, Palladium Catalysis, Oxidation, Cyclization, Enallenes, Aza-Enallenes, Dienallenes, Allenylation, Oxazolidinones, Biomimetic, Arylation, Borylation, Transmetallation
Research subject Organic Chemistry
IdentifiersURN: urn:nbn:se:su:diva-75435ISBN: 978-91-7447-495-4OAI: oai:DiVA.org:su-75435DiVA: diva2:516638
2012-05-24, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
Sigman, Matthew, Professor
Bäckvall, Jan-Erling, Professor
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Manuscript.2012-05-022012-04-182013-01-03Bibliographically approved
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