Diazonamide Synthetic Studies. Reactivity of N-Unsubstituted Benzofuro[2,3-B]Indolines

Benzofuro[2,3-b]indolines undergo ring opening in the presence of base to generate 3H-indolines. The latter can rearrange into 3-arylindoles through an intramol. transfer of the methoxycarbonyl moiety from quaternary carbon to oxygen of phenol. The intermediate 3H-indolines can be isolated upon DMAP-catalyzed O-acylation of the phenol moiety with Boc2O