| Abstract
| - A new approach to the ring EFHG-tetracyclic core fragment of the marine secondary metabolitediazonamide A is described. The route is based on the oxidative rearrangement of 3-arylindole-2-carboxylates. Thus, a range of 3-arylindole-2-carboxylates (3, 8) underwent rearrangement to thecorresponding 3,3-disubstituted oxindoles (4, 9) with migration of the ester group upon treatment withtert-butyl hypochlorite followed by acid. The oxindoles 9 with a 3-[2-(4-methoxybenzyloxy)]phenylsubstituent underwent cyclization to the tetracyclic aminals 11 following N-protection, reduction, andtreatment with methanesulfonic anhydride. The methodology was applied to the tyrosine-indole derivative17 to give the EFHG-tetracyclic core of diazonamide A.
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