ORGANOCATALYTIC HALOFUNCTIONALIZATION OF OLEFINS

Abstract

Enantioselective halocyclization reactions are important for the synthesis of chiral heterocyclic compounds. In the first part of this thesis, a catalytic enantioselective bromocyclization of olefinic amides has been developed. The resulting enantioenriched 2-substituted 3-bromopiperidines can readily be transformed to 3-substituted piperidines through a silver salt-mediated rearrangement. This process has been applied to the synthesis of a dopaminergic drug, Preclamol. Next, an asymmetric synthesis of heterospirocycles through a double-halocyclization strategy which enabled access to a class of chiral novel spirocycles is reported. In a separate study, the intramolecular chloroamidation of olefinic substrates using diphenyl selenide as the catalyst is developed. The reaction conditions were found to be mild and suitable for a wide range of substrates including those which are acid labile. Lastly, preliminary results for the development of a novel proline-based amino-selenocarbamate catalysts were discussed. A derivative of the catalyst, the amino-selenoether, produced encouraging enantioselectivty for halolactonization reactions.