The Coupling-Isomerization Sequence

In comparison to conductive heating in an oil bath under comparable conditions, dielectric heating furnished higher yields in the model reaction at shorter reaction times. Whereas electron deficient (hetero)aryl halides are rapidly coupled and isomerized with triethylamine as a base, for electro neutral and electron rich aryl halides DBU has to be applied to achieve comparable reaction times and yields. Most remarkably the alkyl substituted propargyl alcohol 15 with R = Pr can be successfully transformed giving rise to the enone 16f in moderate isolated yield. 

The mild reaction conditions (relatively weak amine bases, short reaction times) of the CIR of (hetero)aryl halides and l-(hetero)aryl propargyl alcohols opens a modular entry to chalcones, which are as Michael acceptors suitable starting points for consecutive multicomponent syntheses of heterocycles in a one-pot fashion [28, 86]. Both catalytic generations of ynones and enones have set stages for diversity-oriented multicomponent syntheses of heterocycles in a consecutive one-pot fashion. 

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