Resorcinarenyl‐Phosphines in Suzuki–Miyaura Cross‐Coupling Reactions of Aryl Chlorides

Abstract

Two phosphines built on a bowl-shaped resorcin[4]arene skeleton, namely 5-diphenylphosphanyl-and 5-diisopropylphosphanyl-4(24),6(10),12 (16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]arene, have been synthesised and tested in the Suzuki-Miyaura cross-coupling reaction of aryl halides. Combining these ligands with [Pd(OAc) 2 ] resulted in highly active catalysts that allowed the formation of o,oЈ-biphenyls starting from aryl chlorides. The remarkable [a]1364 activities observed possibly arise from 1) the capacity of the phosphines to operate transiently as P,O chelators, thereby increasing the electron density of the metal, and 2) the ability of the ligands to embed metal-organic units, which, when occurring, makes the ligand considerably bulkier so as to disfavour the coordination of a second phosphine. Both features are known to facilitate the oxidative addition step.

Cracking Cavitands: Metal‐Directed Scission of Phosphinyl‐Substituted Resorcinarenes

“…[8] The catalytic outcome contrasts with that observed for classical phosphino-enolato nickel complexes that do not contain an additional phosphine ligand, which typically result in long chain a-olefins under the above conditions. [9] Similar results were obtained when replacing NaBH 4 with NBu 4 BH 4 , thus excluding a cation effect. We tentatively propose that, after activation with borohydride, the borane formed binds the enolato oxygen atom of 6, thereby rendering the latter a weaker donor.…”

“…We have recently reported the synthesis of cavitand 1 , having a diphenylphosphino group grafted to its wider rim 4. The capacity of 1 to behave as a bulky, P‐monodentate ligand was demonstrated in the synthesis of several Pd II complexes.…”

“…[3] We have recently reported the synthesis of cavitand 1, having a diphenylphosphino group grafted to its wider rim. [4] The capacity of 1 to behave as a bulky, P-monodentate ligand was demonstrated in the synthesis of several Pd II complexes. As the phosphino-aryl moiety of 1 is flanked by two ether oxygen atoms which could enable the formation of highly crowded P,O-chelate complexes, we considered that this might influence the strain within the cavity core and possibly modify the cavitand structure.…”

Cavitand Chemistry – Towards Metallocapsular Catalysts

“…Elemental analyses were performed by the Service de Microanalyse, Institut de Chimie, Université de Strasbourg. 5,17‐Dibromo‐4(24),6(10),12(16),18(22)‐tetramethylenedioxy‐2,8,14,20‐tetrapentylresorcin[4]arene ( 1 )[10b] and 5‐diphenylphosphanyl‐4(24),6(10),12(16),18(22)‐tetramethylenedioxy‐2,8,14,20‐tetrapentylresorcin[4]arene were prepared by literature procedures.…”

The Use of Resorcinarene Cavitands in Metal‐Based Catalysis

“…A structural study combined with molecular modelling revealed that monophosphine 8 (Figure ), a cavitand with a P atom directly attached to the upper rim of the bowl, behaves as a ligand with variable bulk, its encumbrance depending on the orientation of the P lone pair . Thus, when the P atom points towards the cavitand axis, its cone angle is by ca.…”