Quatercyclopropane 31 was oxidized, homologated, reduced, and monocyclopropanated to provide the pentacyclopropane alcohol 35. Subsequent deoxygenation of alcohol 35 was effected using N-(phenylthio)succinimide (24) and tributylphosphine followed by Raney nickel desulfurization and deprotection to produce the alcohol 3. This was oxidized, homologated, and hydrolyzed to provide the fatty acid 2. BOP-Cl-mediated coupling of acid 2 and the nucleoside amine 40 gave amide 1, which was spectroscopically identical with an authentic sample of FR-900848 (1).

No abstract

Full structural elucidation of FR-900848, an antifungal pentacyclopropane nucleoside natural product from Streptoverticillium fervens, is reported. A series of model compounds were prepared using multiple asymmetric Simmons−Smith cyclopropanation reactions. Comparisons of spectroscopic data of synthetic alkenes 9 and 10, quatercyclopropanes 11 and 12, and imidazolidines 13 and 14 with FR-900848 and its degradation products 2, 3, and 4 were consistent with the full structural assignment of the natural product as structure 7.

Degradation studies and partial synthesis are used t o establish the full structure and absolute stereochemistry of the nucleoside antifungal agent FR-900848.

Double asymmetric Simmons-Smith cyclopropanation and Whitham elimination were used to prepare ( 8-1,2-bis-[ ( 1 S,2 S)-2-met h y lcyclo p ro py I let hene, the d icycl o p ro py I et h en e u nit of FR-900848.