Design, classification, and strategies of synthesis of modular bidentate ligands based on aryl[2.2]paracyclophane backbone

The aryl[2.2]paracyclophane backbone, which is a “hybrid” of a configurationally rigid [2.2]paracyclophanyl unit and a biphenyl unit, is proposed as a new source for the chiral ligands. Classification of such ligands in accordance with mutual arrangement of the functional substituents and their nature is also introduced. Key strategic approaches to the synthesis of regioisomeric biphenols and hydroxyaldehydes, including Suzuki cross‐coupling reaction, lithiation/electrophilic quench, and chiral resolution, are elaborated. Examples of their further modification and application of several O,O‐ and N,O‐ligands as chiral inductors in asymmetric catalysis are described. © 2005 Wiley‐Liss, Inc. Chirality 18:95–102, 2006.