Evaluation of the Catalytic Capability of cis‐ and trans‐Diquinoxaline Spanned Cavitands

Abstract

Three new cis‐diquinoxaline spanned cavitands were successfully synthesized. These cis‐diphosphinated derivatives were applied in homogeneous gold‐catalyzed dimerization and hydration of alkynes as well as rhodium‐catalyzed styrene hydroformylation. The results were ranked with those obtained with their trans‐diphosphinated isomeric analogues. The structure‐activity relationship employing these two cavitands reveals that the cis‐ or trans‐positioning of the catalyst centers directly influences cooperation between the two metallic atoms to control catalytic activity, reaction profile, and product selectivity. This comparative study provides us an intellectual basis for future catalytic cavitand chemistry and homogeneous catalysis.

Diametric calix[6]arene-based phosphine gold(I) cavitands

“…Thus, a recent evolution of their chemistry concerns the development of novel architectures in which P(III) compounds are incorporated in cavity-shaped macrocycles [5][6][7][8]. In this scenario, calix [4]- [9][10][11][12][13] and resorcin [4]arene [14][15][16][17] are the most exploited cavitands due to their inherent limited flexibility and already proved their ability to control the catalytic activity of late-transition metals and particularly gold(I) catalysts [18][19][20][21][22][23][24][25]. This occurs via strong steric interactions, often outside the macrocycle (Figure 1a) [11], that affect the first coordination sphere of the metal or by creating a spatial confinement around the metal that is thus directed towards the inner cavity (Figure 1b) [26,27].…”

Styrene Hydroformylation with Cavity‐Shaped Ligands

“…Recently, Iwasawa and coll . reported the synthesis and catalytic applications of quinoxaline spanned cavitands 47–49 (Figure ) . The particularity of these introverted ligands is that, due to the steric hindrance generated by the quinoxaline moieties, formation of RhL 2 complex should be excluded.…”

A Resorcin[4]arene-Based Phosphite-Phosphine Ligand for the Branched-Selective Hydroformylation of Alkyl Alkenes

“…Specifically, for the alkene substrates studied, our working hypotheses are that (a) formation of secondary alkyl intermediates by insertion of the alkene into the Rh–H bond is favored by preferential accommodation of the metal species involved in this step within the resorcin[4]­arene cavity compared to those associated with the primary alkyl intermediate and (b) this effect is exacerbated as the substrate chain length increases (Figure ). Supramolecular approaches for controlling activity and selectivity in hydroformylation reactions are attracting increasing attention, and this cavitand-based ligand design concept underscores this potential. The robust and modular nature of the JEKphos design is particularly attractive, and there is considerable scope for optimization of the catalytic performance through variation of pendant phosphine donor, the ligand backbone, and cavity size.…”