Synthesis of spirocyclic diarylfluorenes by one-pot twofold SNAr reactions of diaryl sulfones with diarylmethanes

Article abstract of DOI:10.1021/acs.orglett.5b03384

Treatment of dibenzothiophene dioxides with cyclic diarylmethanes in the presence of KN(SiMe₃)₂ results in the formation of fluorene-based spirocyclic tetraarylmethanes in a single operation. The transformation would proceed via an intermolecular S_NAr reaction of the dioxides with cyclic diarylmethylpotassium followed by intramolecular S_NAr cyclization. This straightforward strategy provides a wide range of spirocyclic diarylfluorenes including unusual ones that are otherwise difficult to synthesize.