Development of new supported asymmetric catalysts based on biopolymers

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This research program has for objectives the regioselective transformation of biopolymers like chitosan to synthesize supported asymmetric catalysts to realize catalytic reactions in organic, aqueous and biphasic media. Chitosan or poly[ß-(1->4)-2-amino-2-deoxy-D-glucopyranose] is polyaminosaccharide obtained from chitin N-deacetylation which is the second more abundant biopolymer after cellulose. Chitin is extracted from crustacean exoskeletons and represents an underexploited resource that abounds in coastal regions of Canada. Each unit of chitosan will be regioselectively transformed in a chelating aminophosphinite or phosphite ligands to obtain a polyligand. Organic soluble polyligands are synthesized by introduction of organic groups at O-6 positions. On the other hand, water soluble polyligands are formed by introduction of polar and ionic groups on primary alcohols. Coordination of these polyligands will be studied by spectroscopy with different metallic centers. Recently, natural products derivatives were studied as asymmetric catalysts. However, chiral support examples used in catalysis are rare. Intrinsic chirality of chitosan will be utilized to induced asymmetry during catalytic reactions. Supported asymmetric catalyst will be used for hydrogenation of model compounds with function as C=C-O (cyclic), C=C-CH2OH and C=C-COOR. Due to the polymeric nature of chitosan, supported catalysts could be recuperated by precipitation or filtration methods. Asymmetric catalysis is the most efficient method to prepare enantiomerically pure compounds and therefore, it represents a major economic importance for chemical industries, and more specifically for pharmaceutical, foods and new material industries. This research program also meets some environmental objectives by the development of soluble asymmetric supports for asymmetric catalysis in aqueous media, biomass valorization and biodegradable polymers transformation.