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2,3-Bis(phenylsulfonyl)-1,3-butadiene as a Reagent for the Synthesis of the Azatricyclic Core of (+/-)-halichlorine

Andrew C Flick, Maria José Arevalo Caballero, Hyoung Ik Lee, Albert Padwa

J Org Chem. 2010 Mar 19;75(6):1992-6.

PMID: 20151655

Abstract:

An efficient stereocontrolled 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)-1,3-butadiene gives rise to a 7-oxa-1-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.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP129271983 1-(Phenylsulfonyl)-3-indolylboronic acid 1-(Phenylsulfonyl)-3-indolylboronic acid 129271-98-3 Price
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