An efficient Cu(ii)-bis(oxazoline)-based polymer immobilised ionic liquid phase catalyst for asymmetric carbon–carbon bond formation

Abstract

The asymmetric Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene and the Mukaiyama-aldol reaction between methylpyruvate and 1-phenyl-1-trimethylsilyloxyethene have been catalysed by heterogeneous copper(II)-bis(oxazoline)-based polymer immobilised ionic liquid phase (PIILP) systems generated from a range of linear and cross linked ionic polymers. In both reactions selectivity and ee were strongly influenced by the choice of polymer. A comparison of the performance of a range of Cu(II)-bis(oxazoline)-PIILP catalyst systems against analogous supported ionic liquid phase (SILP) heterogeneous catalysts as well as their homogeneous counterparts has been undertaken and their relative merits evaluated. Scheme 1 Asymmetric Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene catalysed by 10 mol% Cu(II)-bis(oxazoline) complexes. † Electronic supplementary information (ESI) available: 1 H NMR, 13 C NMR and 19 F NMR spectra for the polymer precursors synthesised. TGA, SEM and FTIR traces for the polymers used. HPLC traces of exo and endo-cycloadducts and aldol adducts formed. See

Recent Advances Utilized in the Recycling of Homogeneous Catalysis

“…An immobilized polymeric ionic liquid phase (PIILP) containing copper (II)‐bis(oxazoline)‐based catalyst was synthesized by Doherty et al . This catalyst then applied for the asymmetric Diels‐Alder reaction of N ‐acryloyl oxazolidinone and cyclopentadiene and the Mukaiyama‐aldol reaction of methyl pyruvate and 1‐phenyl‐1‐trimethylsilyloxyethene under mild reaction condition …”

Ionic Liquids in Asymmetric Synthesis: An Overall View from Reaction Media to Supported Ionic Liquid Catalysis

“…In 2014, Doherty et al studied the asymmetric Diels-Alder reactionb etween N-acryloyloxazolidinone and cyclopentadiene and the Mukaiyama-aldol reactionb etween methyl pyruvate and 1-phenyl-1-trimethylsilyloxyetheneb yu sing copper(II)-bis(oxazoline)-based polymer immobilized ionic liquid catalysts 136 and 137 (Scheme 73). [141] The authors compare this system to their homogeneous counterparts in the abovementioned transforma-tions at 20 8C. In both reactions, the presence of an ionic liquid, either as an additive or as ab ulk solvent, as well as an ionic liquid supported on SiO 2 or multiwalled carbon nanotubes results in conversions and ee values that are highert han those obtained in similar reactions conducted in molecular solvents or ionic-liquid-free systems.…”

Covalently Supported Ionic Liquid Phases: An Advanced Class of Recyclable Catalytic Systems

“…Ionic polymers 96 – 101 were prepared and used as supports for chiral Cu II –bis(oxazoline) complexes and evaluated as catalysts for the asymmetric Diels–Alder and Mukaiyama aldol reactions (Figure ) . Bis(oxazoline) 104 and 105 were used.…”

“…Ionic polymers 96-101 were prepared and used as supports for chiralC u II -bis(oxazoline)c omplexes ande valuated as catalysts for the asymmetric Diels-Alder andM ukaiyama aldol reactions ( Figure 10). [81] Bis(oxazoline) 104 and 105 were used. As ac omparison, the Cu II -bis(oxazoline) complexes were immobilized on SiO 2 or multi-walled carbon nanotubes (CNT) by wet impregnation from dichloromethane by using [C 2 mim][NTf 2 ]a s Scheme38.…”