Efficient Mukaiyama–Aldol Reaction with Aqueous Formaldehyde on a Hydrophobic Mesoporous Lewis Acid Polymer

Abstract

The design of robust water‐compatible solid Lewis acid catalysts in the efficient utilization of aqueous formaldehyde is a challenging task. Herein, we describe an ytterbium triflate containing ordered mesoporous polymer (Yb(OTf)2‐MP) that acts as a highly active and selective Lewis acid catalyst for the Mukaiyama–aldol reaction with aqueous formaldehyde. The unique capacity of hydrophobic surface and ordered mesoporosity was able to stabilize the hydrophilic and hydrophobic reactants simultaneously and catalyze the reaction selectively by minimizing water interference at active sites. Accordingly, it enabled a broad range of silyl enol ethers to be used to create structurally diverse β‐hydroxy carbonyl molecules efficiently. Notably, the process can be scaled up easily to achieve the gram‐scale production of the key intermediate of natural product sarkomycin. Additionally, it is stable under aqueous conditions and can be recovered easily and used repeatedly at least six times.

High‐Performance Heterogeneous Thermocatalysis Caused by Catalyst Wettability Regulation

“…Yb(OTf) 2 −MP with 99 % conversion of HCHO aqueous solution and 96 % selectivity of the target product, higher than many reported results by solid Lewis acid in pure water [98] …”

Synergistic Catalysis of Brønsted Acid and Lewis Acid Coexisted on Ordered Mesoporous Resin for One-Pot Conversion of Glucose to 5-Hydroxymethylfurfural

“…Obviously, the binding energies of ytterbium species in Yb­(OTf) 2 /PhSO 3 H-MPR shifted negatively by about 0.70 eV in comparison with Yb­(OTf) 3 (Figure a). This phenomenon was maybe due to the CF 3 SO 3 - ligands in Yb­(OTf) 3 being replaced by the SO 3 H groups in Yb­(OTf) 2 /PhSO 3 H-MPR, which resulted in the generation of more electron-rich Yb­(III) species . The coordination reaction between Yb­(OTf) 3 and PhSO 3 H-MPR support was further confirm by S 2p XPS spectra.…”

“…This phenomenon was maybe due to the CF 3 SO 3 - ligands in Yb(OTf) 3 being replaced by the SO 3 H groups in Yb(OTf) 2 /PhSO 3 H-MPR, which resulted in the generation of more electron-rich Yb(III) species. 47 The coordination reaction between Yb(OTf) 3 and PhSO 3 H-MPR support was further confirm by S 2p XPS spectra. As shown in Figure 5b, the binding energy of Yb(OTf) 2 /PhSO 3 H-MPR moved positively by 0.10 eV in comparison with PhSO 3 H-MPR.…”

“…This phenomenon was maybe due to the CF 3 SO 3 -ligands in Yb(OTf) 3 being replaced by the SO 3 H groups in Yb(OTf) 2 / PhSO 3 H-MPR, which resulted in the generation of more electron-rich Yb(III) species. 47 The coordination reaction between Yb(OTf) To explore the utility of our Yb(OTf) 2 /PhSO 3 H-MPR catalyst, one-pot isomerization and dehydration cascade reaction by using glucose as the reactant to produce HMF was tested. The blank experiment without Yb(OTf) 2 / PhSO 3 H-MPR catalyst did not give HMF product (Table 3, entry 1).…”

Efficient Recycling of Catalyst‐Solvent Couples from Lewis Acid‐Catalyzed Asymmetric Reactions in Water

“…Previous examples using 5 mol % of Sc(DS) 3 suffered from plateauing yields at around 60 % [27] . Although considerable efforts have been devoted to the design of robust Lewis acid catalysts for the efficient use of aqueous formaldehyde without the need for organic solvents or additives, [14a] asymmetric catalysis for this reaction remained a great challenge [28] . In this study, asymmetric hydroxymethylation catalyzed by 9 g could be run five times with reused catalyst‐solvent couples.…”