Short Diastereoselective Synthesis of the C1-C13 (AB Spiroacetal) and C17-C28 Fragments (CD Spiroacetal) of Spongistatin 1 and 2 through Double Chain-Elongation Reactions
A unique and practical synthetic sequence for rapid access to polyketides and to further the spiroacetals derived from them, which utilizes a bidirectional Hosomi-Sakurai allylation approach around key allylsilanes in the synthesis of the AB and CD ring systems of spongistatin 1 and 2, is reported. The synthesis of the AB spiroacetal 9 requires 13 steps, with a longest linear sequence of seven steps in an overall yield of 27%. The synthesis of the CD spiroacetal 13 requires 15 steps, with a longest linear sequence of 11 steps in an overall yield of 30%. Both syntheses start from but-3-enol.
Keywords: double chain elongation ; enantioselectivity ; Hosomi-Sakurai reaction ; spiro compounds ; spongistatin ; Stereocontrolled Total-Synthesis ; Marine Macrolide Synthesis ; Sponge Hyrtios-Altum ; Formal Total-Synthesis ; Potent Cytotoxic Macrolides ; F-Ring Subunit ; Altohyrtin-A ; Natural-Products ; Modular Approach ; Ef-Fragment
Record created on 2011-12-16, modified on 2016-08-09