Synthesis of the Core Structure of Palhinine A

Abstract

AbstractWe present a strategy to the core structure of the alkaloid palhinine A passing through a 2,5‐difunctionalized cyclohexenone. This enone was prepared by a domino Michael/aldol condensation sequence. An allylation reaction on the cyclohexenone followed by oxy‐Cope rearrangement introduced an allyl group at C3. After the generation of an aldehyde function on the terminus of the C5 substituent, an intramolecular aldol reaction led to a bicyclo[2.2.2]octanone. The five‐membered ring of the core structure could be established by an intramolecular nitrile oxide‐alkene [3+2]‐cycloaddition. Prior to this key transformation, the keto function was converted to an alkene and the allyl group to an oxime.