Interrupted Carbonyl-Olefin Metathesis Via Oxygen Atom Transfer

Schindler et al. have reported a novel interrupted carbonyl-olefin metathesis method via acid catalysis.¹⁾ Their group has recently discovered an additional mechanistic pathway involving a key oxetane intermediate through the synthesis of a variety of tetrahydrofluorenes, a class of compounds that have wide appeal in material science,²⁾ are frequent cores to terpenes,³⁾ and are central to several pharmaceuticals.^4,5) The synthesis of tetrahydrofluorenes via this method employs triflic acid as the acid catalyst and features a broad substrate scope varying from good to excellent yield. The aromatic moiety is tolerant to strongly electron donating, electron withdrawing, and heteroatomatic (e.g. thiophene) groups. Substrates bearing an isomerizable olefin are also well tolerated under the reaction conditions, and offer for more structural diversity on the central ring. This new synthetic method shows enormous potential and applications within chemistry, materials science, and pharmaceuticals.