PREPARATION OF NEW, MONOSACCHARIDE-BASED BIFUNCTIONAL ORGANOCATALYSTS
Károly Ágoston
Péter Fügedi
RCNS-HAS, Institute of Organic Chemistry, Department of Organocatalysis and Supramolecular Chemistry, Budapest
In recent years bifunctional organocatalysis which combines H-bond donors and Lewis base functionalities in a single asymmetric molecular scaffold received great attention. In our institute there is already a “tradition” for the preparation and examination of these thiourea-based catalysts together with the theoretical investigation of the mechanism of the catalysed reactions.[1]
In the literature there are some examples of the preparation of monosaccharide-containing bifunctional organocatalysts and of their use to catalyse aza-Henry or Michael reactions.[2] In these catalysts the carbohydrate moiety was located on the side of the molecule and not in between the two catalytic centres. To our knowledge there is only one example in the literature where a monosaccharide residue was used as a real scaffold to connect the two active centres thereby defining the selectivity of the catalysed reaction.[3]
We have initiated a project to prepare new bifunctional thiourea catalysts starting from D-glucose. Several different catalyst candidates have been prepared, where the carbohydrate is flanked by the two catalytic groups.
[1] Vakulya, B.; Varga, Sz.; Csámpai, A.; Soós, T. Org. Lett., 2005, 7, 1967-1969. Hamza, A.; Schubert, G.; Soós, T.; Pápai, I; J. Am. Chem. Soc, 2006, 128, 13151-13160.
[2] Examples: Lu, A.; Gao, P.; Wu, Y.; Wang, Y.; Zhou, Z.; Tang, C. Org. Biomol. Chem., 2009, 7, 3141-3147. Ma, H.; Liu, K.; Zhang, F.-G.; Zhu, C.-L.; Nie, Y.; Ma, J.-A. J. Org. Chem., 2010, 75, 1402-1409.
[3] Puglisi, A.; Benaglia, M.; Raimondi, L.; Lay, L.; Poletti L. Org. Biomol. Chem., 2011, 9, 3295-3302.
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