A Polystyrene‐Bound Triphenylphosphine Gold(I) Catalyst for the Glycosylation of Glycosyl ortho‐Hexynylbenzoates

Abstract

The efficacy of the heterogeneous polystyrenebound triphenylphosphine gold(I) catalyst 3 (PS-[Ph 3 PAu I NTf 2 ]; PS = polystyrene;T f = trifluoromethanesulfonyl) in the activation of glycosyl ortho-hexynylbenzoates for glycosylationi sd emonstrated. The shelf-stable catalyst 3 (andi ts precursor 2,P S-[Ph 3 PAu I Cl]) were fully characterized by elemental analysis, X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM), and showed remarkable catalytic activities and recyclability in glycosylation reactions as wella si nt he skeletal rearrangemento ft he 1,6enyne 4.E DS analysis demonstrated that the phosphine ligand binds the gold strongly and prevents the leaching of the metal.

Anchoring Triazole-Gold(I) Complex into Porous Organic Polymer To Boost the Stability and Reactivity of Gold(I) Catalyst

“…To avoid this problem, subsequently, they reported another heterogeneous gold(I) catalyst with polystyrene-supported phosphine ligand using Ag + as an activation reagent (Scheme 1B). 7 Although this catalyst could catalyze several alkyne and allene activation reactions, significantly reduced reactivity was observed after each cycle, likely caused by gold decomposition and a potential influence from AgCl. Thus, the avoidance of AgCl waste in catalyst activation and the improvement of the stability of [L-Au] + are essential toward the realization of highly efficient heterogeneous gold(I) catalysts.…”

“…Although this catalyst showed good reactivity toward some interesting transformations (such as the enyne cyclization), it suffered from gold leaching each cycle due to the dynamic coordination of triazole ligand. To avoid this problem, subsequently, they reported another heterogeneous gold­(I) catalyst with polystyrene-supported phosphine ligand using Ag + as an activation reagent (Scheme B) . Although this catalyst could catalyze several alkyne and allene activation reactions, significantly reduced reactivity was observed after each cycle, likely caused by gold decomposition and a potential influence from AgCl.…”

Silica-Immobilized NHC-Gold(I) Complexes: Versatile Catalysts for the Functionalization of Alkynes under Batch and Continuous Flow Conditions

“…Interestingly, Yu et al reported the use of two recyclable polystyrene-supported gold catalysts in the cycloisomerization of 1,6-enyne 16 to give tetrahydropyridine 17 and alcohol 18 with a 6 mol % catalyst load. The product selectivity of these PS-immobilized gold catalysts then resembles that of homogeneous phosphine complexes .…”

Glycosylation via Transition‐Metal Catalysis: Challenges and Opportunities

“…3) Development of solid‐supported transition metal complexes, especially those from precious metals, for efficient glycosylation is appealing and challenging, as recycling precious and expensive transition metals would greatly save the cost and improve the practicality of such glycosylation processes. As an excellent example, Yu has developed a polystyrene‐bound triphenylphosphine gold(I) catalyst for glycosylation . 4) Despite some success, use of transition metal catalysis for stereoselective construction of challenging glycosidic linkages, such as 2‐deoxy‐α‐ and β‐glycosides, 1,2‐ cis ‐glycosidic linkages (e.g., α‐glucosides and β‐mannosides), and α‐sialosides, has been rather limited.…”

“…Besides cationic Ph 3 PAuOTf, during the course of research Yu and co‐workers developed several versions of gold catalysts for the activation of glycosyl ortho ‐hexynylbenzoates, such as Ph 3 PAuNTf 2 , a Au I π‐bis( tert ‐butyldimethylsilyl)acetylene triphenylphosphine complex, a polystyrene‐bound triphenylphosphine gold(I) catalyst …”