Introverted Phosphorus‐Au Cavitands for Catalytic Use

Abstract

A preparative synthesis of an inwardly directed phosphoramidite-Au complex is described and a description of some of its catalytic performance. The molecular structure was determined by crystallographic analysis, which disclosed that the phosphoramidite ligand points "out" and places the complexed

An Introverted Bis‐Au Cavitand and Its Catalytic Dimerization of Terminal Alkynes

“…[16] In seeking to develop a reactivity profile for 2, we followed the examples that we had previously explored for 1. [9] In examining the 2-mediated Conia-ene [17] reaction we were surprised to find no evidence of cyclization -instead, bis-Au cavitand 2 brought two alkynes together to result in a dimerization event (Scheme 2). The resulting enyne was isolated as the major product in 45 % yield.…”

“…We again conducted thorough control experiments: (1) utilizing the mono-gold complex [9] shown in panel (a) of Scheme 1, (2) using commercially available AuCl·PPh 3 , (3) using phosphorus-free AuCl·S(CH 3 ) 2 , and (4) using the gold-free host 1. Dimers were not observed in any case.…”

“…[9] The arrangement of one Au atom, pointing inward and flanked by 3 aromatic walls, provided a new architecture for alkyne catalysis; both hydration and Conia-ene reactions were demonstrated using this cavitand system. We think this arrangement holds great promise for further investigations.…”

Gold Catalysis in (Supra)Molecular Cages to Control Reactivity and Selectivity

“…Iwasawa and co‐workers developed a resorcin[4]arene‐based cavitand, containing a phosphorous atom that can function as a ligand that coordinates to a metal center . The lone pair of the P atom is oriented toward the cavity space, so a coordinating metal ion is directed into the cavity .…”

“…This strategy was previously described by Rebek and co‐workers using palladium, and coordination complexes with rhodium and platinum have been reported as well. Iwasawa and co‐workers attached a gold center to the resorcin[4]arene cavitand (Figure ) . The crystal structure showed that the gold center pointed inward and was surrounded by the walls of the cavity.…”