3,6-DIDEOXY-3,6-IMINOHEXOPYRANOSIDES AS ORGANOCATALYSTS FOR THE ASYMMETRIC MICHAEL ADDITION

摘要

Asymmetric reactions using organocatalysts have become a focus of attention as environmentally friendly and metal-free transformations. In the field of carbohydrate chemistry, various kinds of organocatalysts have been synthesized so far for the asymmetric carbon-carbon bond formation. For example, Tripathi's group reported an asymmetric aldol reaction between acetone and aromatic aldehydes catalyzed by glycosyl-β-amino acids. Kunz's group also reported an asymmetric Strecker and Mannich reactions catalyzed by glucosaminylurea derivatives. These results suggest that chemical yield, diastereoselectivity, and enantioselectivity depend strongly on the configuration and the bulkiness of the substituents in the pyranosidic or furanosidic ring of the catalysts. Therefore, we thought that sugar-based derivatives were suitable organocatalyst for asymmetric reactions. We would like to report this time an asymmetric Michael addition of cyclohexanone to nitroolefins using 3,6-dideoxy-3,6-iminohexo-pyranosides as a new class of organocatalyst.