Synthesis of planar chiral pseudo–ortho-substituted aryl[2.2]paracyclophanes by stepwise successive palladium-catalyzed coupling reactions

Planar Chiral [2.2]Paracyclophane-Based Bisoxazoline Ligands: Design, Synthesis, and Use in Cu-Catalyzed Inter- and Intramolecular Asymmetric O–H Insertion Reactions

“…Organic extracts were dried over anhydrous Na 2 SO 4 . Ligands (S p )-1b, 1c, 1d and 4a, 35) compounds rac-5 36) and 6, 35) and diazo esters 2, 21) 7 43) and 10a-e 17) were prepared according to the literature procedure. To a suspension of (S p )-1d (7.3 mg, 0.013 mmol) and MS5A (315 mg) in CH 2 Cl 2 (1 mL) were added NaBAr F (11.2 mg, 0.0126 mmol) and CuCl (1.0 mg, 0.010 mmol) at room temperature under an argon atmosphere.…”

“…We reported in a short communication that the ligands showed good enantioselectivities in intermolecular ethanolic and phenolic O-H insertions. 35) We now report the effects of the introduction of central chirality of the oxazoline ring in the PCP-based Box ligand on intermolecular ethanolic O-H insertion. Details of inter-and intramolecular aromatic O-H insertion reactions catalyzed by PCP-based Box (S p )-1-Cu complexes are also given.…”

“…The Box ligands 4 with both planar and central chiralities proved to be unsuitable for Cu-catalyzed intermolecular ethanolic O-H insertion, therefore we next investigated the use of the Box ligands (S p )-1, with only planar chirality, in inter-and intramolecular aromatic O-H insertion reactions. For the intermolecular phenolic O-H insertion reaction of ethyl α-diazopropionate (7), 22,27) the enantioselectivity of the isopropyl-substituted ligand (S p )-1d was better than that of phenyl-substituted (S p )-1b, and 80% ee was achieved, with the S configuration being preferred 35) (Table 2, entries 1, 3). The insertion reaction proceeded smoothly at room temperature, and the use of CuCl as a Cu source gave the highest enantiocontrol, but the product yield was lower than that obtained with Cu(OTf) 2 (entry 6).…”

“…Considering the similarity between O-H insertion and N-H insertion, and the observation that the preferred absolute stereochemistries of all products (ethanolic O-H insertion product 3, intramolecular aliphatic O-H insertion product, 35) and inter-and intra-molecular aromatic O-H insertion products 9 and 11) obtained with the Box (S p )-1-Cu catalysts are opposite to those obtained with Zhou's Spirobox (S a ,S,S)-5-Cu, 22,[24][25][26] the C 2 -symmetric catalyst conformation during the Cu-catalyzed O-H insertion reaction is proposed to be that shown in Fig. 3b.…”

Enantiopure planar chiral [2.2]paracyclophanes: Synthesis and applications in asymmetric organocatalysis

“…85 In addition to PhanePhos and its derivatives, planar chiral pCp-based bifunctional phosphine-phenol compounds have been prepared and used as catalysts in metal-free reactions (Scheme 23). [86][87][88][89] To access these compounds, 4-bromo-12-hydroxy[2.2] paracyclophane (S p )-47 is first isolated through a mono metalation of enantiomerically pure 4,12-dibromo[2.2]paracyclophane (S p )-21, followed by a reaction with trimethylborate, and oxidation of the resulting product with hydrogen peroxide and sodium hydroxide. The obtained key intermediate (S p )-47 is then engaged into a Suzuki-Miyaura coupling in the presence of phosphinylboronic esters.…”