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Synthesis of the C(29)−C(45) Bis-pyran Subunit (E−F) of Spongistatin 1 (Altohyrtin A)

2000; American Chemical Society; Volume: 65; Issue: 25 Linguagem: Inglês

10.1021/jo001236o

1520-6904

Glenn C. Micalizio, Anatoly N. Pinchuk, William Roush,

Alkaloids: synthesis and pharmacology

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 α-alkoxyallylation reactions using the γ-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.