A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes

• DOI: 10.1038/ncomms4470
• Publication Date: 2014-04-07T11:25:55Z
• Authors: Yanzhao Wang; Zhixun Wang; Yuxue Li; Gongde Wu; Zheng Cao; Liming Zhang
• Keywords: Alkyne; Moiety; Amide

Most homogenous gold catalyses demand ≥ 0.5 mol% catalyst loading. Owing to the high cost of gold, these reactions are unlikely to be applicable in medium- or large-scale applications. Here we disclose a novel ligand design based on the privileged (1,1'-biphenyl)-2-ylphosphine framework that offers a potentially general approach to dramatically lowering catalyst loading. In this design, an amide group at the 3'-position of the ligand framework directs and promotes nucleophilic attack at the ligand gold complex-activated alkyne, which is unprecedented in homogenous gold catalysis considering the spatial challenge of using ligand to reach anti-approaching nucleophile in a linear P-Au-alkyne centroid structure. With such a ligand, the gold(I) complex becomes highly efficient in catalysing acid addition to alkynes, with a turnover number up to 99,000. Density functional theory calculations support the role of the amide moiety in directing the attack of carboxylic acid via hydrogen bonding.