Synthesis of Substituted Phenanthrene by Iron(III)-Catalyzed Intramolecular Alkyne–Carbonyl Metathesis

An efficient synthesis of functionalized phenanthrenes
has been
developed for the first time involving an iron­(III)-catalyzed intramolecular
coupling of 2′-alkynyl-biphenyl-2-carbaldehydes. A broad range
of functionalized phenanthrene derivatives could be obtained in the
present method in moderate to good yields with high chemo- and regioselectivity.
This transformation can also be applied to the synthesis of an angularly
fused tetracyclic compound. This method offers several advantages
such as high selectivity, mild reaction conditions, and easy availability
of starting materials.