Glycosides with 1,2-cis linkages are commonly found in naturally occurring molecules (e.g. KRN7000, heparan sulphate) and there has been much interest in development of stereoselective methods for synthesis of such linkages.1Thus far the utilization of non-participating protecting groups, solvent assisted glycosidations, and various glycosyl donors have lead to respectable anomeric ratios in particular cases.The utilisation of anomerisation as a means towards 1,2-cis linkages has been reported in the literature2-5, the majority of these methods involve glycosides which have protecting groups that could be considerd more electron releasing. These reactions are not applicable to a wide range of substrates. The Murphy group have previously shown that chelation induced anomerisation of 1,2-trans glycosidic linkages can be successful in the presence of acyl protecting groups. Although acyl groups are more electron withdrawing, highly stereoselective synthesis of 1,2-cis glycosides can be achieved.7In this presentation anomerisation studies not reported to date will be discussed.1. Demchenko A. V. Synlett 2003 , 1225 �12402. Wang, Y.; Cheon, H.-S.; Kishi, Y. Chem. Asian J., 2008  , 3, 319-326.3. Olsson, J. D. M.; Eriksson, L.; Lahmann, M.; Oscarson, S. J. Org. Chem, 2008  , 73, 7181-7188.4. Manabe, S.; Ishii, K.; Satoh, H.; Ito, Y. Tettrahedron 2011  , 67, 9966-9974.5. Lemieux, R. U.; Hindsgaul, O. Carb. Res., 1980  , 82, 195-206.7. Pilgrim, W.; Murphy, P. V. J. Org. Chem. 2010, 75, 6747�6755

Synthesis of 1,2-c<i>is</i> glycosides via chelation induced anomerisation

246th National Meeting (2013)

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Synthesis of 1,2-cis glycosides via chelation induced anomerisation