Unsaturated aldehydes as alkene equivalents in the Diels-Alder reaction

Esben Taarning, Robert Madsen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

A one-pot procedure is described for using alpha,beta-unsaturated aldehydes as olefin equivalents in the Diels-Alder reaction. The method combines the normal electron demand cycloaddition with aldehyde dienophiles and the rhodium-catalyzed decarbonylation of aldehydes to afford cyclohexenes with no electron-withdrawing substituents. In this way, the aldehyde group serves as a traceless control element to direct the cycloaddition reaction. The Diels-Alder reactions are performed in a diglyme solution in the presence of a catalytic amount of boron trifluoride etherate. Subsequent quenching of the Lewis acid, addition of 0.3% of [Rh-(dppp)(2)Cl] and heating to reflux achieves the ensuing decarbonylation to afford the product cyclohexenes. Under these conditions, acrolein, crotonaldehyde and cinnamaldehyde have been reacted with a variety of 1,3-dienes to afford cyclohexenes in overall yields between 53 and 88%. In these transformations, the three aldehydes serve as equivalents of ethylene, propylene and styrene, respectively.
Original languageEnglish
JournalChemistry: A European Journal
Volume14
Issue number18
Pages (from-to)5638-5644
ISSN0947-6539
DOIs
Publication statusPublished - 2008

Keywords

  • cyclo-alkenes
  • Diels-Alder reaction
  • aldehydes
  • decarbonylation
  • homogeneous catalysis

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