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

Abstract

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.

Síntesis de compuestos aza-bicíclicos por ciclación intramolecular de imidas

“…De este modo, la cetona III-117 podría ser preparada a partir de la adición de succinimida sobre la cetona a,b-insaturada III-119, que puede ser preparada a través de una secuencia de tres etapas conocidas, que han sido reportadas de manera independiente y consisten en: a) ozonólisis de alcohol homoalílico bencilado III-120 que genera el aldehído III-121 208…”