Asymmetric Carbon‐Carbon Bond Forming Reactions Catalysed by Metal(II) Bis(oxazoline) Complexes Immobilized using Supported Ionic Liquids

Abstract

A series of bis(oxazoline) metal(II) complexes has been supported on silica and carbon supports by non-covalent immobilisation using an ionic liquid. The catalytic performance of these solids was compared for the enantioselective Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene and the Mukaiyama-aldol reaction between methyl pyruvate and 1-methoxy-1-trimethylsilyloxypropene. In both reactions the enantioselectivity was strongly influenced by the choice of support displaying enantioselectivies (ee values) up to 40% higher than those conducted under homogeneous reaction conditions.

Catalytic oxidation of cyclohexane with hydrogen peroxide and a tetracopper(II) complex in an ionic liquid

“…The 1/H 2 O 2 /[bmim][PF 6 ] system, in comparison with the conventional 1/H 2 O 2 /NCMe homogeneous one having the most common organic solvent [3(a)], revealed significant improvements on the catalytic performance of 1, in terms of products yield, TON, reaction time, selectivity towards cyclohexanone, easy recycling and reuse (not possible in homogeneous conditions). They are of significance towards the establishment of a green catalytic process.…”

“…The generality of the above advantages in the field of alkane oxidation should also be tested by extending the investigation to other alkanes and a variety of catalysts. 6 ] up to 5 mL total volume, 50 8C, 120 min. b Based on GC analysis, after treatment with PPh 3 ; moles of cyclohexanol + cyclohexanone per 100 moles of cyclohexane.…”

“…Cyclic voltammetry (CV) studies were undertaken in 0. 6 ], at a platinum disc working electrode (d = 0.5 mm) and at room temperature. A Pt wire was employed as the counter-electrode.…”

Heterogeneous Jacobsen's catalyst on alkoxyl‐modified zirconium poly (styrene‐phenylvinylphosphonate)‐phosphate (ZPS‐PVPA) for asymmetric epoxidation

“…The development of heterogeneous catalysts able to promote enantioselective organic reactions is a field of growing interest. A major advantage of the use of a heterogeneous catalyst for reactions is the ease with which it can be recovered and subsequently reused . Therefore, many efforts have been taken to anchor these catalysts on polymer, organic or inorganic, and ionic liquids .…”

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

“…The drop in catalyst activity upon recycle for PIILP systems based on catalyst A is thought to be mainly attributed to the build-up of cyclopentadiene dimer 18 on the support surface, as has been previously observed in other SILP catalysed Diels-Alder reactions. 3 This proposal was supported by a reduction in conversion from 86% to 32% and a drop in ee from 90% to 19% upon addition of cyclopentadiene dimer (10 molar equivalents with respect to substrate) to the ethereal layer of a freshly prepared PIILP system derived from IP-1 and catalyst A. While the PIILP and PIILP-IL catalysts performed poorly upon recycle the SiO 2 -based SILP system maintained high conversions and good ee's upon recycle.…”