90608-91-6Relevant academic research and scientific papers
2,3-Bis(phenylsuIfonyl)-l,3-butadiene as a reagent for the synthesis of the azatricyclic core of (±)-halichlorine
Flick, Andrew C.,Jose, Maria,Caballero, Arevalo,Lee, Hyoung Ik,Padwa, Albert
, p. 1992 - 1996 (2010)
Chemical Equation Presented An efficient stereo-controlled route to the azatricyclic core of an advanced halichlorine intermediate is described. Reaction of the oxime derived from 2-(oxo-cyclopentyl)acetic acid ethyl ester with 2,3-bis(phenylsulfonyl)-l,3-butadiene gives rise to a 7-oxa-l-azanorbornane cycloadduct in high yield. The formation of the bicyclic isoxazolidine arises from conjugate addition of the oxime onto the diene to afford a transient nitrone that then undergoes an intramolecular dipolar cycloaddition. Treatment of the cycloadduct with 5% Na/Hg results in reductive nitrogen-oxygen bond cleavage to furnish a spirocyclic piperidinone, which was further elaborated to an advanced intermediate employed in an earlier synthesis of halichlorine.
