Final Report Summary - HALOCHIRAL (Asymmetric Halogenation of Olefins Involving Intermolecular Nucleophiles)
Therefore, the project HALOCHIRAL was dedicated to the development of a general methodology for the asymmetric halogenation of olefins in conjunction with an intermolecular nucleophilic attack on the generated electrophilic intermediate. This is expected to improve the scope of feasible olefins and also increase the range of possible nucleophiles. In methodology relying on intramolecular attack of the nucleophile, there is always the need for the synthesis of complex achiral substrates, which will be circumvented when intermolecular nucleophiles can be used instead.
The chiral products should be obtained with a high degree of regio- and enantioselectivity and the compounds needed to form the stoichiometric reagent can in principle be recycled. Such a method will be strongly embraced by the pharmaceutical industry, who are in desperate need of new, efficient ways to generate chirality, and by many other fields such as the material sciences.
In this project synthetic routes were developed for the first enantioselective electrophilic halogenation reagents. One of the ligands synthesized allows investigation of the electronic needs for stabilization of the key intermediate, whereas the second provides a model compound for the first intermolecular enantioselective halogenation reagent.
The obtained results are an important step on the way to a deepened understanding of how substituents can be used to control the kinetics of the planned halogenation reaction. Synthetic access has been established towards the production of ligands incorporating chiral centers in order to produce a chiral environment during the halogenation reaction that is close enough to the reaction site to transfer the chirality to the product. In continuation of this work, a pathway for the asymmetric halogenation of olefins may be developed.