(R)- and (S)-6,6′-dimethyl- and 6,6′-dimethoxy-2,2′-diiodo-1,1′-biphenyls: Versatile intermediates for the synthesis of atropisomeric diphosphine ligands

Catalytic Asymmetric Bromine‐Lithium Exchange: A New Tool to Build Axial Chirality

“…[12] This new dilithiated species has already been shown, by the team of Cereghetti, to afford numerous diphosphine ligands. [13] Since the direct arylation did not work (see above), the reverse arylation was attempted. Phenylzinc chloride could react, under Pd catalysis, with 31, selectively with the iodides and not at all with the bromides.…”

“…General Remarks 1 H (400 MHz or 300 MHz) and 13 C (100 MHz or 75 MHz) NMR spectra were recorded in CDCl 3 or MeOD and chemical shifts are given in ppm relative to residual CDCl 3 or MeOD. The evolution of the reactions was followed by GC-MS Hewlett Packard (EI mode) HP6890-5973.…”

Asymmetric Bromine–Lithium Exchange: Application toward the Synthesis of New Biaryl‐Diphosphine Ligands

“…However, the reaction with Ph 2 PCl resulted in poor yield, and more importantly, a serious loss of ee , from 72% to 24%. This phenomenon may be ascribed to the formation of an ate‐complex which appeared to be highly problematic in terms of optical purity conservation10 (Scheme ).…”

Catalytic Palladium Phosphination: Modular Synthesis of C1‐Symmetric Biaryl‐Based Diphosphines

“…Keywords: biaryls · cross-coupling · lithiation · palladium · phosphorus product have been carried out and no general approach has been developed to avoid its formation. [13] Similarly, our group has shown that an increased torsion angle between the two phenyl rings is necessary for the formation of bis(diphenylphosphino)biphenyls to prevail and, in some cases, the phosphafluorene has not been observed. [14] Continuing our research, we have reported the synthesis of the first C 1 -symmetric MeO-BIPHEP analogue 1 a.…”