Collect. Czech. Chem. Commun. 2006, 71, 667-678

Intensification of a Reaction by the Addition of a Minor Amount of Solvent: Diels-Alder Reaction of 2H-Pyran-2-ones with Alkynes

Krištof Kranjc and Marijan Kočevar*

Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana, Slovenia


Diels-Alder transformation of substituted 3-benzoylamino-2H-pyran-2-ones 1 with a variety of alkynes 2 under microwave (MW) irradiation in a closed system can be intensified in a novel way by addition of a minor amount of butan-1-ol. When the reagents are not volatile under the used conditions, the reactions do not seem to be influenced by the addition of butan-1-ol, as demonstrated by the cycloaddition of a fused 2H-pyran-2-one 5 with N-ethylmaleimide (6) giving adduct 7.

Keywords: Cycloadditions; Diels-Alder reactions; Alkynes; Microwaves; Green chemistry; Aniline derivatives; Benzenes; Pyranones.

References: 46 live references.