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Chiral Bidentate Oxazoline Ligands on Different Supports: Preparation and Application
Markku Oila
Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Chemical Technology for public examination and debate in Auditorium KE2 (Komppa Auditorium) at Helsinki University of Technology (Espoo, Finland) on the 16th of February, 2008, at 12 noon.
Overview in PDF format (ISBN 978-951-22-8960-8) [2538 KB]
Dissertation is also available in print (ISBN 978-951-22-8959-2)
Abstract
The oxazoline core is found in many active pharmaceuticals. It has for some decades been recognized as a useful synthon in chemical synthesis and, more recently, as a ligand in catalysis. The PyOX-core (2-(2'-pyridyl)oxazoline), consisting of two heteroatom rings, was accidentally formed for the first time in the early 1970's. The excellence of PyOX-structures as metal catalyst ligands was recognized from the late 1980's onwards, an observation generating a need for more efficient syntheses of enantiopure, functionalized PyOX-ligands.
In the first part of this thesis, an efficient synthesis route to form an enantiopure PyOX-based thiolate compound was optimized. This method was then applied in the synthesis of a series of enantiopure solid-supported compounds.
The novel PyOX-derived thiolate was used to form a novel chiral gold nanoligand. Its gold core was to the best of our knowledge smaller than before in experimental chemistry. This nanoparticle was used as a ligand in a known asymmetric test reaction, giving a reasonable selectivity.
Novel PyOX-ligands, synthesized in this thesis, were also used as chiral ligands in the asymmetric Henry reaction, an application previously unknown for PyOX-ligands.
Finally, the methodology used to prepare substituted and chiral PyOX-ligands was applied to the synthesis of a new, enantiopure ligand family, the IndOX (2-(2'-indolyl)oxazoline).
This thesis has yielded an optimized methodology to form substituted enantiopure bidentate oxazoline ligands (PyOX and IndOX) in a simple and efficient way. The methodology was also applied on ligand formation on solid polymer and semi-soluble nano supports. These ligands were tested for known asymmetric test reactions and a new test reaction for PyOX-ligands (Henry reaction) was introduced.
This thesis consists of an overview and of the following 5 publications:
- Markku J. Oila, Jan E. Tois, and Ari M. P. Koskinen. 2005. Synthesis of a novel carboxy functionalized PyOX-ligand. Tetrahedron Letters, volume 46, pages 967-969. © 2005 Elsevier Science. By permission.
- Markku J. Oila, Jan E. Tois, and Ari M. P. Koskinen. 2005. Ligand creation via linking—a rapid and convenient method for construction of novel supported PyOX-ligands. Tetrahedron, volume 61, pages 10748-10756. © 2005 Elsevier Science. By permission.
- Markku J. Oila and Ari M. P. Koskinen. 2006. Chirally modified gold nanoparticles: nanostructured chiral ligands for catalysis. Arkivoc (Archive for Organic Chemistry), volume 2006, part (xv), pages 76-83. © 2006 by authors.
- Markku J. Oila, Jan E. Tois, and Ari M. P. Koskinen. 2008. A new application for PyOX-ligands: the asymmetric Henry reaction. Letters in Organic Chemistry, volume 5, number 1, pages 11-16. © 2008 Bentham Science Publishers. By permission.
- Markku J. Oila, Jan E. Tois, and Ari M. P. Koskinen. 2008. Mild and efficient synthesis of 2-indole-2'-oxazolines at room temperature—a simple access to novel IndOX ligands. Synthetic Communications, volume 38, number 3, pages 361-370.
Keywords: PyOX-ligand, IndOX-ligand, solid-phase chemistry, supramolecular chemistry, gold nanoparticle, asymmetric catalysis, enantioselectivity
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© 2008 Helsinki University of Technology
Last update 2011-05-26