Generation and Cycloaddition of o-Quinodimethane in Aqueous Medium

Abstract

o-Quinodimethane can be generated from =α,α'-dihalo-o-xylenes using zinc in aqueous solution. In the presence of activated dienophiles cycloadducts can be obtained directly. Catalysis with tris-triphenylphosphine ruthenium(II) dichloride reduces side reactions such as reduction and polymerisation and improves the yield. This is the first example of an organometallic cyclisation in aqueous medium using dihalo compounds.

Keywords

• Dehalogenation
• zinc
• Diels-Alder reaction
• Ru catalysis
• aqueous solvent