A general strategy for the total synthesis of the antitumor agent apoptolidin (1) is proposed, and the chemical synthesis of the defined key building blocks (4, 5, 6, 8, and 9) in their enantiomerically pure forms is described. The projected total synthesis calls for a dithiane coupling reaction to construct the C(20)-C(21) bond, a Stille coupling reaction to form the C(11)-C(12) bond, and a Yamaguchi macrolactonization to assemble the macrolide ring, as well as two glycosidation reactions to fuse the carbohydrate units onto the molecule. First and second generation syntheses to the required fragments for apoptolidin (1) are described.

The total synthesis of the novel immunosuppressant sanglifehrin A (SFA, 1) is described. The approach is flexible, convergent, and stereoselective. The use of Paterson's aldol methodology was pivotal for the preparation of the novel, highly substituted spirolactam fragment of SFA. The 22-membered macrocyclic core of the molecule and the coupling of this fragment to the spirolactam moiety were successfully achieved using selective intra-and intermolecular Stille reactions, respectively. Carbodiimide-based protocols were employed for the synthesis of the tripeptide backbone.

No abstract

No abstract