Synthesis of the C1–C26 Northern Portion of Azaspiracid‐1: Kinetic versus Thermodynamic Control of the Formation of the Bis‐spiroketal

Abstract

North–South divide: An efficient synthesis of the entire C1–C26 (northern) portion of azaspiracid-1 is disclosed (see picture). Key transformations include the formation of a bis-spiroketal, the oxidation of a sulfone at C10 to form a β,γ-unsaturated ketone, a tandem Wadsworth–Emmons/hetero-Michael addition to construct ring D, and the highly selective hydroxylation at C20. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z503733_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.