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Iridium-Catalyzed Asymmetric Hydrogenation of Substituted Pyridines
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
Stockholm University.
2013 (English)In: Asian Journal of Organic Chemistry, ISSN 2193-5807, Vol. 2, no 12, p. 1061-1065Article in journal (Refereed) Published
Abstract [en]

Asymmetric hydrogenation of ortho-substituted pyridines catalyzed by N,P-ligated iridium is demonstrated. To facilitate this reaction, the aromaticity of the pyridines was weakened by forming N-iminopyridium ylides. The reactions give very high conversions, and after a single recrystallization, excellent ee of up to 98 % was obtained. This method lends itself to the synthesis of chiral piperidine building blocks.

Place, publisher, year, edition, pages
2013. Vol. 2, no 12, p. 1061-1065
Keywords [en]
hydrogenation, iridium, N-iminopyridium ylides, pyridines, selective catalysis
National Category
Organic Chemistry Inorganic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-212412DOI: 10.1002/ajoc.201300160ISI: 000328218000008OAI: oai:DiVA.org:uu-212412DiVA, id: diva2:677721
Available from: 2013-12-10 Created: 2013-12-10 Last updated: 2017-01-25Bibliographically approved
In thesis
1. Iridium Catalysed Asymmetric Hydrogenation of Pyridines
Open this publication in new window or tab >>Iridium Catalysed Asymmetric Hydrogenation of Pyridines
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents the hydrogenation of substituted pyridines using N,P-ligated iridium catalystsin homogeneous media. These iridium catalysts were developed within this research group in thepast decade. This method of hydrogenation is highly stereoselective, and in several cases good to excellent ees were obtained.The hydrogenation of substituted pyridines was studied: by screening for the catalyst giving thehighest conversion and ee, by optimising the reaction conditions and by attempting to improve existingcatalysts. New substrates were synthesised for this process, in particular alkyl substituted Nprotectedpyridines. Their reduction provided chiral piperidines, which could be used as chiralbuilding blocks once deprotected.

Place, publisher, year, edition, pages
Uppsala: Uppsala universitet, 2013. p. 34
Keywords
hydrogenation, pyridine, catalytic, Iridium
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-212413 (URN)
Presentation
2013-05-31, Uppsala, 12:41 (English)
Opponent
Supervisors
Available from: 2013-12-11 Created: 2013-12-10 Last updated: 2017-01-25Bibliographically approved
2. Noble Metal Catalysed Reductions and Rearrangements
Open this publication in new window or tab >>Noble Metal Catalysed Reductions and Rearrangements
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The focus of this thesis has been organometallic catalysis applied to compounds containing heteroatoms which are usually poisonous to metal catalysts, by channelling their innate reactivity advantageously. The studies described in this thesis concentrate, in the first part, on iridium catalysed asymmetric hydrogenation (papers I and II) and in the second part, on gold catalysed internal rearrangements (papers III and IV). In each case, two classes of compounds are studied: pyridinium salts or sulphurous compounds. The asymmetric hydrogenation of pyridinium compounds was performed with 2% loading of N,P-ligated Ir catalyst with I2 additive (paper I) to achieve moderate to good enantiomeric excess (up to 98%). In paper II, olefinic sulphones were hydrogenated with an efficient 0.5% catalytic loading. In most cases full conversion was obtained and with good to excellent ees (up to 99%). The products of these reductions are chiral compounds, which could constitute further chemical building blocks. Palladium and gold were used sequentially in paper III, in order to perform a “Click” thiol-yne reaction followed by a semi-Pinacol rearrangement, leading to isolated yields of up to 98%. In paper IV The gold catalysed rearrangement of alkyl-pyridinium diynes was conducted, with a number of substrates providing >90% NMR yield. A highly selective hydrogenation was performed with a heterogeneous palladium catalyst to yield single diastereomer products. This methodology consists of up to three steps, with two catalysts in one pot.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. p. 63
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1337
National Category
Organic Chemistry
Research subject
Chemistry with specialization in Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-272383 (URN)978-91-554-9453-7 (ISBN)
Public defence
2016-02-25, B/B21, BMC, Husargatan 3, Uppsala, 09:30 (English)
Opponent
Supervisors
Available from: 2016-02-03 Created: 2016-01-13 Last updated: 2016-02-12

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Publisher's full texthttp://dx.doi.org/10.1002/ajoc.201300160

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Cadu, AlbanUpadhyay, Puspesh K.

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