An efficient one-pot approach to phenanthrene derivatives using a catalyzed tandem Ullmann-pinacol coupling reaction

In the presence of catalyst (Ph3P)2NiCl2 and reductant Zn, the Ullmann reactions of ortho-halo aryl aldehydes generate biaryl-dialdehydes and zinc halides. Subsequently, ZnX2 can catalyze the intramolecular pinacol coupling reaction of biaryl-dialdehydes to form 9,10-dihydrophenanthrene-9,10-diols. One-pot synthesis of 9-phenanthrols can be achieved using this strategy.