A novel class of bidentate ligands with a conformationally flexible biphenyl unit built into a planar chiral [2.2]paracyclophane backbone

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

“…Enantiomeric and diastereomeric analyses were carried out by HPLC on Chiracel-AD chiral column (hexane/iPrOH = 4:1, 1 ml/min). The Suzuki reactions 4 and enantioselective Et 2 Zn addition to benzaldehyde 6 were performed according to typical procedures.…”

“…For compound 2, the energy barrier to rotation (17 -18 kcal mol À1 ) was estimated with variable-temperature 1 H NMR techniques from the coalescence temperature (390 K) for the methoxy signals. 4 The other possibility to fix the axial chiral conformation could be realized during the complexation with metal. 10 Thus the combination of the planar chirality of aryl [2.2]paracyclophane backbone with the axial chirality of the biaryl fragment could allow one the fine-tuning of the chiral environment between the catalyst and substrate.…”

“…11 The coupling of paracyclophanyl halides and arylboronic acids was found to be more efficient than that of paracyclophanyl boronic acids and aryl halides. 4 As a rule, ortho-substituted (OMe, OMOM, CHO) arylboronic acids were used.…”

“…The first Suzuki coupling reaction in [2.2]paracyclophane series, which is one of the key steps in the formation of the titled backbone, was reported by us in a recent preliminary publication. 4 …”

Novel strategy for the synthesis of chiral pseudo-ortho-substituted hydroxy[2.2]paracyclophane-based ligands from the resolved 4-bromo-12-hydroxy[2.2]paracyclophane as a parent compound

“…For instance, phenol 1 was used as the parent compound for the synthesis of FHPC 2 (R = H), 3c,4a,6 a paracyclophanyl analog of salicylic aldehyde; orthohydroxyketones 2 (R = Me, Ph) 7 in turn served as the starting compounds in the synthesis of a family of bi-, tri-and tetradentate imine ligands 8 and chiral aminophenols]; 9 1,3-oxazol-2-one 3; 10 'bridged' biphenols 4; 11 diparacyclophanyl biphenol 5; 12 and arylparacyclophanes 6 (X = OH, OMe). 2a, 13 Phenol 1 was also used in the design of a class of bis-bifunctional ligands 7 2d by oxidation of 1 to the corresponding quinone 14 followed by the addition of functionally substituted aryllithium derivatives. Compounds 2-7 ( Fig.…”