Perkin communications. Acid-catalysed rearrangement of the Diels–Alder adducts of activated quinones
Abstract
The Diels–Alder adducts (1)–(5) in the presence of the hydrochloric acid undergo a 4a,5 carbon–carbon bond fission to give rearranged compounds of type (9), (10), or the dihydrobenzofurans (11)–(14). Compound (16), obtained by hydrolysis of the adduct (15), rearranges to (17) in the presence of ethanol and silica gel.