Rapid assembly of tetrahydrodibenzofurans and tetrahydrocarbazoles from benzene and o-iodophenols and o-iodoanilines: reductive radical arylation of benzene in action

In the presence of catalytic benzeneselenol, generated in situ from diphenyl diselenide, tributyltin hydride brings about the radical addition of ortho-functionalized aryl iodides to benzene giving aryl cyclohexadienes. These may then be cyclized by means of standard electrophilic reagents. The use of o-methoxycarbamoyliodobenzene leads to a tetrahydrocarbazole, whereas o-iodobenzoic acid provides a tetrahydrodibenzopyranone. o-Iodophenols lead, overall, to tetrahydrodibenzofurans.