Synthesis of Unsymmetrical o-Biphenols and o-Binaphthols via Silicon-Tethered Pd-Catalyzed C-H Arylation

A mild, practical, and efficient method for the synthesis of unsymmetrical o-biphenols (including o-phenol-naphthols and o-binaphthols) has been developed. Unsymmetrical bis-aryloxy silanes, which were readily prepared in a semi-one-pot fashion, underwent the Pd-catalyzed intramolecular arylation followed by a routine TBAF desilylation step to furnish valuable unsymmetrical biphenols without necessity of isolation of seven-membered intermediates. The excellent functional group tolerance allows for synthesis of a variety of functionalized o-biphenols and o-binaphthols from easily available staring materials.