Gör ditt examensarbete hos oss på avdelningen för organisk kemi!

The term “organocatalysis” describes the acceleration of chemical reactions through the addition of a substoichiometric quantity of an organic compound. The interest in this field has increased spectacularly in the last few years as result of both the novelty of the concept and as a result of the high efficiency and selectivity of many organocatalytic reactions.[i] In particullar, chiral amines e.g. proline and pyrrolidine-derivatives, have proven to be particularly useful as catalysts in enamine and iminium ion activation.

However, organocatalysis has not yet gained good foothold in the area of total synthesis. The specific aim of this project is to develop stereoselective organocatalytic reactions that can serve as key steps for stereoselective carbon skeleton construction in total synthesis of natural products.

For more information please contact: Johan Franzén (jfranze@kth.se) 08-7908125

[i] For recent reviews on organocatalysis, see: (a) Dalko, P. L.; Moisan, L. Angew. Chem., Int. Ed. 2004, 43, 5138. (b) Berkessel, A.; Gröger, H. Asymmetric Organocatalysis; WCH: Weinheim, Germany, 2004. (c) Seayed, J.; List, B. Org. Biomol. Chem. 2005, 3, 719. (d) Jarvo, E. R.; Scott, J. M. Tetrahedron 2002, 58, 2481.

Oxidations are fundamental processes in organic synthesis that in most cases relay on the use of stochiometric amounts of a heavy metal complex as the oxidating agent. Despite the fact that oxidations are so frequently used in organic synthesis, methods for enantioselective catalytic oxidations are very sparsely described. This project involves the development of novel methods for asymmetric oxidations that relay on the use of enviormently friendly stochiometric oxidating agents.

In this project an enantioselective approach toward oxidative carbocyclizations using elementary iodine as the stochiometrich oxidant is studied (Scheme 1). The approach is to use a chiral organic molecule as a nucleophilc activator (*Activ.) that can react with iodine and generate a chiral electrophilic iodination reagent (I-*Activ.). I-*Activ. can then react in an enantioselective fashion with an olefin (1) to give an intermediate cyclic iodonium species (2). The final step involves an intramolecular electrophilic aromatic substitution to give the bicyclic product 3 in an overall enantioselective iodoarylation of the double bond.

Scheme 1

The aim of this project is to develop a chiral activator that is capable to enantioselective catalyze the cyclization described in Scheme 1.

For more information please contact: Johan Franzén (jfranze@kth.se) 08-7908125

Bioorganisk kemi - Receptorstyrd syntes av proteasinhibitorer

Projektet syftar till att ta fram nya inhibitorer till en viss typ av enzymer (proteaser) med hjälp av så kallad receptorstyrd syntes från kombinatoriska bibliotek. Detta är en ny teknik som underlättar såväl framställning som identifiering av nya inhibitorer med t ex farmakologisk aktivitet. Projektet omfattar både syntes av aktiva substanser och biologisk testning/screening mot enzymer.

Mer information ges av: Olof Ramström

Total Synthesis of Viracept; a Potent HIV Protease Inhibitor

Viracept 1 is a potent anti HIV-agent exerting its activity by selective inhibition of the virus protease enzyme. This enzyme is responsible for the cleavage of polyproteins and the maturation of new viral particles and is an attractive target for HIV therapy.

We are currently interested in an alternative synthetic approach towards 1 and structural derivatives thereof. This approach is based on the propensity of vinylic epoxides to be selectively ring-opened in the allylic position by hard nucleophiles, to assemble the highly functionalised pentene fragment 3. This fragment will serve as a key intermediate in the total synthesis of 1.

Interested?

Please contact
Per Restorp, Organic Chemistry (restorp@kth.se) 08-7909148 or
Peter Somfai, Organic Chemistry (somfai@kth.se) 08-7906960

Supramolekylär kemi - Syntetiska enzymer

Projektet syftar till att designa och syntetisera artificiella receptorer med katalytisk verkan. Som utgångspunkt för receptorerna kommer cyclodextriner (CD) att användas. Dessa är naturligt förekommande (primitiva) värdmolekyler som har förmåga att binda lipofila gästmolekyler i vatten. Den katalytiska effekten kan sedan åstadkommas genom att dekorera cyclodextrinerna på lämpligt sätt. Projektet omfattar både syntes av receptorer och analys av deras katalytiska verkan.

Mer information ges av: Olof Ramström

SYNTHESIS AND SURFACE CHEMICAL CHARACTERIZATION OF NOVEL SURFACTANTS

Surfactants are important molecules. Every day we come in contact with several different types of surfactants and it is therefore important to understand their mode of action and to develop new and more efficient ones. Normal surfactants consist of a hydrophilic part and a hydrophobic part that are connected by a spacer.

We have developed a general synthesis of surfactants with the generic structure 1. All possible stereoisomers of 1 can be readily prepared and we are currently investigating the influence of the relative sereochemistry of the surfactants on their physical properties.

An interesting continuation of this project is to prepare the corresponding dimer, its generic structure 2 is shown below, and investigate its surface chemical properties. This particular type of dimer has not been previously prepared why its qualities as a surfactant are difficult to predict (this also makes the project exciting!).

The project is a collaboration between the divisions of Organic Chemistry and Surface Chemistry at KTH and the diploma work will consist of:

• Synthesis of dimeric surfactant 2 at the division of Organic Chemistry.
• Investigating its surface chemical properties at the division of Surface Chemistry.

Print out this project as a pdf-file by clicking here.

Contact persons:

Peter Somfai, phone: 790 6960
e-mail: somfai@kth.se (organic chemistry).

Per Claesson, phone: 790 9972
e-mail: per.claesson@surfchem.kth.se (surface chemistry).