INTENSIFICATION OF A REACTION BY THE ADDITION OF A MINOR AMOUNT OF SOLVENT:DIELS-ALDER REACTION OF 2H-PYRAN-2-EONS WITH ALKYNES

摘要

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.