DDQ-Induced, Anomeric Specific, and Diastereoselective Benzylic Glycosidation: A Novel Approach to Heterocyclic Anthracycline Antibiotics
摘要:
A novel and efficient method for the oxidative glycosidation at the heterosubstituted benzylic positions with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) is described. The reaction is stereospecific with 3-substituted isochromans and isothiochroman, as well as diastereoselective with non-3-substituted isochromans. The glycosidation with a mixture of alpha- and beta-anomeric free sugars gives alpha-glycosides with absolute stereochemical control on the anomeric center. The synthetic utility of this novel methodology is demonstrated by a short, efficient, and stereoselective total synthesis of heteroanthracycline antitumor reagents.