A Phosphanyl‐Substituted Benzo‐1,3,2‐Dioxaborol as Ambiphilic Bifunctional Lewis Donor–Acceptor Unit

Abstract

Condensation of 3-[(diphenylphosphanyl)methyl]benzene-1,2-diol (1) with phenyl boronic acid gave a phosphane-functionalised benzo-1,3,2-dioxaborol 3. The ability of this species to act as a Lewis base through the P-centered donor and as a Lewis acid through the B-centered acceptor sites was demonstrated by the reactions with (cod)PdCl 2 and some nitrogen donors (4-dimethylaminopyridine, diaza-[2.2.2]-bicyclooctane, pyridine). These reactions yielded either palladium-phosphane complexes or amine-borane adducts that were characterised by spectroscopic data and, in some cases, by single-crystal X-ray diffraction studies. Reactions of a Pd complex of the phosphane-functionalised benzo-1,3,2-di-

On the Immobilisation of Catechol Phosphane Palladium Complexes on Titania

“…The isotropic chemical shifts (Table 1) allow the assignment of these signals to the trans isomers which is also in accord with the known crystal structure of 4. [10,20] As additional lines attributable to the cis isomers were undetectable, the solid-state NMR spectra can be seen as an indication that both the crystalline and surface-tethered complexes contain exclusively the trans isomers. The line widths of the signals for the surface-bound complexes on TiO 2 were somewhat larger (in case of 4) or similar (in case of 7) as those for the pure crystalline complexes whereas the NP-TiO 2 -supported complexes displayed an increase in linewidths by nearly an order of magnitude (Figure 1).…”

“…Complexes [PdCl 2 (1b) 2 ] (4) and [PdCl 2 (1a) 2 ] (7) were prepared as described [10] from 1a,b and [PdCl 2 (cod)] (cod = 1,5-cyclooctadiene). Characterisation of the novel complex 7 by solution NMR spectroscopy reveals, as in the case of 4, [10] the presence of a mixture of cis and trans isomers, which can be easily distinguished by their characteristic 31 P NMR spectroscopic data [10,11,19] [δ( 31 P) = 33.3 ppm (cis isomer), 20.3 ppm (trans isomer), isomer ratio approx.…”

“…[8,9] These compounds embody transitionmetal bis(phosphane) complexes of a template-based chelate ligand and were shown to be active catalysts in CϪC cross coupling reactions. [8] The individual binding sites of 1 can also be addressed specifically, thus enabling the construction of complexes such as 3 [9] and 4 [10] in which the ligands bind exclusively by means of the phosphorus atom or the catechol unit.…”

Regioselective Coupling Reactions of Coumarins with Aldehydes or Di‐tert‐butyl Peroxide (DTBP) through a C(sp2)–H Functionalization Process

“…The required P, O‐chelates 7a , b are readily available by treating phosphane complexes 6a , b 9 or 2:1 mixtures of 2 and [M′Cl 2 (cod)] (M′ = Pd, Pt) with excess triethylamine in EtOH solution (Scheme ).…”

Coordination Chemistry of Neutral (Ln)–Z Amphoteric and Ambiphilic Ligands

“…The formation of the boronic ester functionality on the am-biphilic ligand, starting from the corresponding diol, is possible prior to or after phosphane coordination on palladium. [45] …”