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 Brønsted acidity of the solid.