title: Synthesis of the C(29)-C(45) bis-pyran subunit (E-F) of spongistatin 1 (Altohyrtin A).
abstract: A synthesis of the C(29)-C(45) bis-pyran subunit 2 of spongistatin 1 (1a) is described. The synthesis proceeds in 19 steps from the chiral aldehyde ent-7, and features highly diastereoselective alpha-alkoxyallylation reactions using the gamma-alkoxy substituted allylstannanes 17 and 19, as well as a thermodynamically controlled intramolecular Michael addition to close the F-ring pyran. The E ring was assembled via the Mukaiyama aldol reaction of F-ring methyl ketone 3 and the 2,3-syn aldehyde 4.
authors: Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors: G C
authors: GC
authors: Micalizio
authors: A N
authors: AN
authors: Pinchuk
authors: W R
authors: WR
authors: Roush
mesh_terms: D004988:Ethers, Cyclic / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D018942:Macrolides; D011714:Pyrans / Q000138:chemical synthesis* / Q000737:chemistry; D000095702:Polyether Toxins
chemical_list: D004988:Ethers, Cyclic; D007783:Lactones; D018942:Macrolides; D011714:Pyrans; C083856:spongistatin 1; D000095702:Polyether Toxins