Gold(I) Complexation of Phosphanoxy‐Substituted Phosphaalkenes for Activation‐Free LAuCl Catalysis

• Published in: Chemistry : a European journal Vol. 27; no. 7; pp. 2469 - 2475
• Main Authors: Kato, Miki, Ueta, Yasuhiro, Ito, Shigekazu
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.02.2021
• Subjects: Alcohols; Alkynes; Catalysis; Catalysts; Catalytic activity; Chemical reactions; Chemistry; Complexation; conformational isomerism; Coordination; coordination chemistry; electron density distribution; Gold; gold catalysis; Isomerization; phosphaalkenes; Phosphorus; Phosphorus removal; Silver; Substitutes; conformational isomerism; electron density distribution; gold catalysis; phosphaalkenes; coordination chemistry
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202004281

The phosphanoxy‐substituted phosphaalkene bearing the P=C−O−P skeleton can be prepared from diphosphene Mes*P=PMes* (Mes*=2,4,6‐tBu3C6H2), and their use for catalysis is of interest. In this paper, complexation of the phosphanoxy‐substituted phosphaalkenes with gold are investigated, and the catalytic activity of the mono‐ and bis(chlorogold) complexes are subsequently evaluated. Reaction of the P=C−O−P compound with (tht)AuCl (tht=tetrahydrothiophene) showed dominant coordination on the sp3 phosphorus, and complete coordination on the sp2 phosphorus required removal of tetrahydrothiophene. Atoms In Molecules (AIM) analysis based on the X‐ray structure of the mono(chlorogold) complex indicated a pseudo coordinating interaction between the gold center and the P=C unit. The bis(chlorogold) complexes displayed conformational isomerism, and catalyzed the cycloisomerization/alkoxycyclization of 1,6‐enyne and for hydration of terminal alkyne without activation treatment. Even the mono(chlorogold) complexes catalyzed the alkoxycyclization reactions without a silver co‐catalyst, indicating that the alcohols were effective in activating the AuCl unit. Phosphanoxy‐substituted phosphaalkenes are employed to develop the chemistry of LAuCl complexes. The bis(chlorogold) complexes displayed conformational isomerism, and the relatively sensitive P(sp2)−Au bonding was effective for activation‐free gold catalysis. Even the mono(chlorogold) complexes including the Au⋅⋅⋅P=C pseudo coordination interaction enabled activation‐free reactions including with alcohols.