KINETIC-STUDIES ON THE REARRANGEMENT OF DIELS-ALDER ADDUCTS OF ACTIVATED BENZOQUINONES WITH (E)-1-TRIMETHYLSILOXYBUTA-1,3-DIENE

The acid-induced rearrangement of the 4a-derivatives of hylsiloxy-4a,5 ,8,8a-tetrahydro-1,4-naphthoquinones 4-6 in dioxane-water and THF-wate r solutions is the subject of a kinetic study. On the basis of spectro photometric evidence, the incursion of 5-hydroxy-tetrahydronaphthalene -1,4-dione and arylcrotonaldehyde type intermediates in formation of t he benzofuran from adducts 4-6, is proposed. The effects on the reacti ons of the solvent composition, temperature, hydrochloric acid concent ration, and substituent nature in the adducts are discussed. The resul ts are rationalized and a schematic representation is provided.