Indole β-nucleophilic substitution. Part 2. Formation of a [2]benzoxepino[4,3-b]indole and a pyrido[4′,3′:5,6]oxepino[3,2-b]indole

The syntheses are described of [2]benzoxepino[4,3-b]indol-11(6H,12H)-one, (12a) and 12-methylpyrido[4′,3′:3,4]oxepino[3,2-b]indol-5(6H,12H)-one, (5), by sequences involving the first examples of intramolecular nucleophilic substitution at an indole β-position, with departure of phenylsulphinate as leaving group from nitrogen. The spectroscopic and chemical evidence supporting the structures for these new heterocyclic systems, and thus by implication the operation of indole β-nucleophilic substitution, are detailed.