KINETIC-STUDIES ON THE REARRANGEMENT OF DIELS-ALDER ADDUCTS OF ACTIVATED BENZOQUINONES WITH (E)-1-TRIMETHYLSILOXYBUTA-1,3-DIENE
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Date
1993
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Abstract
The acid-induced rearrangement of the 4a-derivatives of 4a,5-trans-4a,8a-cis-5-trimethylsiloxy-4a,5,8,8a-tetrahydro-1,4-naphthoquinones 4-6 in dioxane-water and THF-water solutions is the subject of a kinetic study. On the basis of spectrophotometric evidence, the incursion of 5-hydroxy-tetrahydronaphthalene-1,4-dione and arylcrotonaldehyde type intermediates in formation of the benzofuran from adducts 4-6, is proposed. The effects on the reactions of the solvent composition, temperature, hydrochloric acid concentration, and substituent nature in the adducts are discussed. The results are rationalized and a schematic representation is provided.