The Rearrangement of Peroxides for the Construction of Fluorophoric 1,4-Benzoxazin-3-one Derivatives

An unprecedented skeletal rearrangement of 3-(tert-butylperoxy)indolin-2-one using a tin catalyst has been developed. This rearrangement is highly selective to afford a series of fluorophoric (Z)-2-arylidene and alkylidene-2H-benzo[b][1,4]oxazin-3(4H)-one derivatives in good to excellent yield. In contrast with Sn(OTf)(2), the reaction of 3-(tert-butylperoxy)indolin-2-one derivatives with FeCl3 afforded the Hock fragmentation product via C-C bond cleavage.