Asimicin, total synthesis

The total synthesis of (+)-asimicin also uses this methodology for the introduction of the butenolide in one of the final steps, the formation of 117 from 116 (Scheme 15.34) [78], Owing to the small scale (18 pirn o 1), an excess of catalyst had to be used. 

Scheme 10-25. Formal total synthesis of trilobacin and asimicin by Ruan and Mootoo.

The total synthesis of (+)-asimicin, which belongs to the family of Annonaceous acetogenins, was completed by E. Keinan and co-workers. In order to create one of the tetrahydrofuran rings stereospecifically, an intramolecular Williamson ether synthesis was performed between a secondary alcohol and a secondary mesylate using pyridine as the base. 

Carbonylation of alkenyl iodides according to the above protocol was applied by Hoye and co-workers to the total synthesis of naturally occurring butenohdcs. An example from the synthesis of (+)-asimicin and (+)-bullacitin is shown in Scheme 4. 

Marshall JA, Sabatini JJ. An outside-in approach to adjacent bistetrahydrofuran annonaceous acetogenins with C2 core symmetry. Total synthesis of asimicin and a C32 analogue. Org. Lett. 2006 8 3557-3560. 

In 1995, Hoye published total syntheses of (+)-asimicin (69) and (+)-bullatacin (70), which differ only in their configurations at C-24 [97J. Here, the AD was used for the synthesis of two key fragments, 81 and 82. 

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