ORGMET. CARB. · Organometallic Reactions in Carbohydrate Chemistry

Organometallic Reactions in Carbohydrate Chemistry

The Researcher has been investigating organometallic reactions on carbohydrates. The Researcher has investigated the use of organozinc reagents for addition of vinyl and phenyl groups to carbohydrate hemiacetals. The objective of this project was to obtain better diastereoselectivity than was obtained using organomagnesium (Grignard) reagents. Mixing a vinylmagnesium or phenylmagnesium reagent with a zinc source, i.e. a dialkyl zinc (methyl or ethyl) solution or zinc bromide with appropriate stoichiometry, gave an organometallic reagent, a trialkylzincate that transferred vinyl or phenyl to a carbohydrate hemiacetal with a diastereoselectivity more favouring the 1,2-chelation product than when the Grignard reagent alone was used. The products of these addition reactions underwent stereospecific debenzylative cyclisation to give tetrahydrofurans with acid catalysis. This work completed a study begun by an earlier post-doc in the group, R. Cribiu. These results were published: Cribiu, R.; Borbas, K.E.; Cumpstey, I., On the synthesis of vinyl and phenyl C-furanosides by stereospecific debenzylative cycloetherification, Tetrahedron, 2009, 65, 2022-2031. doi:10.1016/j.tet.2009.01.014 The Researcher has also been working on two further projects, the results of which have not yet been published. These are: amination and oxidation of carbohydrate hydroxyl groups by transition metal catalysed hydride transfer chemistry; pseudodisaccharide formation by palladium-catalysed allylic amination of carbasugars. The Researcher has also been synthesising starting materials using multi-step synthesis, often on multi-gram scales. These starting materials would include partially protected monosaccharides; aminated monosaccharides (C-N bond formation was necessary); carbasugars (C-C bond formation and ring-closure using Ruthenium catalysed ring-closing metathesis). Contact details for the Scientist in charge: Ian Cumpstey, Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden Tel: +46 8 16 2481; Email: cumpstey@organ.su.se, ian.cumpstey@sjc.oxon.org Contact details for the Researcher: K. Eszter Borbas, Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, SwedenTel: +46 8 16 2720; Email: eszter@organ.su.se

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