Synthetic studies on enfumafungin: stereoselective synthesis of the CD ring segment.

The stereoselective synthesis of the right-hand segment of enfumafungin, a potent antifungal agent isolated from a Hormonema sp., was achieved. The contiguous two quaternary carbon atoms at the angular positions of the trans -fused CD ring system was constructed through the stereoselective reduction of 4-cyano-3,4-dimethyl-2-cyclohexen-1-one and the Johnson–Claisen rearrangement. After elongation of the side chains, the D ring was formed via a stereoselective intramolecular conjugate addition reaction which was originally developed by our laboratory. [ABSTRACT FROM AUTHOR]