POCl 3 /Sulfoxide-Promoted Synthesis of Indolizino[8,7- b ]indoles.

A mild chlorocyclization of pyrrole-tethered indoles has been realized using POCl 3 as the chlorine source and tetramethylene sulfoxide as the promoter. A variety of chlorinated indolizino[8,7- b ]indole derivatives have been constructed efficiently under this reaction system in moderate to good yields (19 examples, up to 93% yield).