Chemistry of aminophenols. Part 3: First synthesis of nitrobenzo[b]furans via a coupling–cyclization approach

The first synthesis of 4-, 5-, and 6-nitrobenzo[b]furans has been achieved via the Sonogashira cross-coupling reaction of 2-iodonitrophenol acetates prepared from commercially available and inexpensive 2-aminonitrophenols. The obtained 2-alkynylnitrophenol acetates were subjected to a KOtBu-promoted cyclization at room temperature to form nitrobenzo[b]furans. Examples of the synthesis of other substituted benzo[b]furans and the one-pot coupling–cyclization are given.