Pillar[n]arene-based phosphine ligands: synthesis, coordination chemistry and application in selective Au(i) catalysis.

We report a divergent and modular synthetic strategy for the functionalization of pillar[n]arenes, enabling the synthesis of a comprehensive library of 17 mono- and bisphosphine ligands. By leveraging a Pd-catalyzed phosphinylation of A1/A2-ditriflate-pillararenes, we demonstrate that precise stoichiometric control permits the isolation of bifunctional phosphine-triflate intermediates. These scaffolds serve as versatile pivotal intermediates for the construction of rim-differentiated bisphosphines and hybrid aryl-phosphine derivatives via sequential Pd-catalyzed cross-couplings. Coordination studies with gold(i) precursors, supported by X-ray crystallography, reveal a certain degree of conformational plasticity inherent to the macrocyclic backbone. The catalytic utility of these macromolecular ligands was validated in the gold(i)-catalyzed cycloisomerization of 1,6-enynes, where several derivatives exhibited excellent levels of regioselectivity.