Total synthesis of herbicidin C and aureonuclemycin: impasses and new avenues.

The undecose nucleoside antibiotics herbicidin C and aureonuclemycin are biologically highly active and represent challenging targets for total synthesis. Herein, the gradual evolution of our synthetic strategy toward these natural products is described in detail. The initial route encompasses metalate addition chemistry but suffers from poor stereochemical control. In contrast, the ultimately successful strategy benefits from a variety of reagent-controlled stereoselective transformations, including a surprisingly facile and highly diastereoselective N-glycosylation process. The presented work also describes new building blocks that might find further application in carbohydrate chemistry.