Ethylene-linked bis(phenol) ligands: efficient synthesis, Ti(IV) coordination chemistry, and Lewis acid catalysis

We report herein an efficient synthesis of a series of chelating bis(aryloxide) ligands that can be diverged at a late stage to generate a variety of structures. Based on structural differences between linked and unlinked analogs of six-coordinate acid–base adducts of (ArO)2TiCl2(dmpe), a hypothesis predicted that a difference between the two structure types would be apparent when the compounds shuttled between four- and six-coordinate structures. Comparing their efficiencies in the Lewis acid accelerated Diels–Alder reaction, however, did not support this notion.