Microwave activation of alumina and its use as a catalyst in synthetic reactions

Microwave irradiation is a simple and efficient method of activating gamma alumina. Alumina activated in this manner is an excellent medium in which to carry out the Diels-Alder reaction and, in conjunction with additional microwave irradiation, the Claisen rearrangement. Several 2-allylphenols formed in the Claisen rearrangement rapidly undergo ring closure on alumina to form dihydrobenzofurans demonstrating the Bronsted acidity of the solid.