Structure and reactivity of new phosphine ligands containing the hemi-labile sulfone moiety

Abstract

New heterofunctional phosphine ligands have been synthesised, incorporating the substitutionally labile sulfone and sulfonamide moieties as chelating groups, which display activity in the palladium-catalysed Suzuki and amination cross-coupling reactions. Single-crystal X-ray diffraction studies of the complexes formed with [Pd(mu-Cl)(dmba)] (dmba-H = N,N-dimethylbenzylamine) highlight the coordinating nature of these ligands; showing the formation of a bis chelate complex through a six-membered Pd-P-C-C-S-O ring with the sulfonamide class of ligands.

Generation of an Aromatic Amide‐Derived Phosphane (Aphos) Library by Self‐Assisted Molecular Editing and Applications of Aphos in Room‐Temperature Suzuki–Miyaura Reactions

“…We reasoned that the broad peak c at 26.1 ppm may be assigned for the P-monodentate complex 9 a, which might exhibit a dynamic 31 P NMR profile due to the conformational flexibility of the bulky and non-coordinated amide moiety. [24] Alternatively, the broad peak c seen in Figure 4b-d might be a consequence of the equilibrium between 9 a and 9 a' in which one Aphos molecule acts as both P-and O-monodentate donor to different Pd species. If this is true, it should account for the observation that the broad peak c disappeared in the presence of a large excess of 21.…”

“…[24] We report here a detailed account of our studies on the synthesis and screening of an Aphos library for discovery of a highly efficient precatalyst that promotes roomtemperature Suzuki-Miyaura cross-coupling of unactivated and sterically hindered aryl chlorides. [25] Results and Discussion…”

“…[28] A similar P,O-chelating Pd II complex of the sulfonamide phosphane 6 a was characterized by X-ray crystal structural analysis. [24] Moreover, the P-monodentate Pd II complex of 6 a was established in the solid state, but it demonstrated dynamic behavior in the solution phase and was possibly in equilibrium with the P,Ochelating complex. [24] Such fluctuation in P-monodentate and P,O-bidentate coordination modes of tertiary aromatic amide/sulfonA C H T U N G T R E N N U N G amide phosphanes is believed to be the structural basis for the observed catalytic efficacy in SuzukiMiyaura cross-coupling reactions.…”

“…[24] Moreover, the P-monodentate Pd II complex of 6 a was established in the solid state, but it demonstrated dynamic behavior in the solution phase and was possibly in equilibrium with the P,Ochelating complex. [24] Such fluctuation in P-monodentate and P,O-bidentate coordination modes of tertiary aromatic amide/sulfonA C H T U N G T R E N N U N G amide phosphanes is believed to be the structural basis for the observed catalytic efficacy in SuzukiMiyaura cross-coupling reactions. It is advantageous that tertiary aromatic amides can offer steric bulkiness through the N,N-dialkyl unit and do not exhibit an N-donor function.…”

New carboalkoxybis(triphenylphosphine)palladium(II) cationic complexes: Synthesis, characterization, reactivity and role in the catalytic hydrocarboalkoxylation of ethene. X-ray structure of trans-[Pd(COOMe)(TsO)(PPh3)2]·2CHCl3

“…The CCD exploration returned about 20 Pd mononuclear complexes with the metal showing a Pd-O-S-C moiety and a Pd environment similar to the one found in our compound [45][46][47][48][49][50][51][52][53][54][55]. [17].…”