Highly Enantioselective Epoxidation of Unfunctionalized Olefins Catalyzed by Chiral Jacobsen’s Catalyst Immobilized on Phenoxy‐Modified Zirconium Poly(syrene‐phenylvinylphos‐ phonate)phosphate

Abstract

Chiral Jacobsens catalyst was axially immobilized onto phenoxy-modified zirconium poly-A C H T U N G T R E N N U N G (styrene-phenylvinylphosphonate)phosphate (ZPS-PVPA). The immobilized catalysts show comparable ee values for asymmetric epoxidation of styrene and much higher ee values for a-methylstyrene (73.7% vs. 54.0%) and indene (99.9% vs. 65.0%) than the homogeneous Jacobsens catalyst. Moreover, the assynthesized catalysts are relatively stable and can be recycled at least five times without significant loss of activity and enantioselectivity. A point worth emphasizing is that the heterogeneous catalysts afforded remarkable increases of conversion and ee values in the absence of expensive O-coordinating axial bases for the asymmetric epoxidation of olefins, especially for the epoxidation of a-methylstyrene (conversion: from 24.3% to 99.9%; ee: from 29.4% to 73.7%), which may overcome the last obstacle for the potential industry application of chiral Jacobsens catalyst.

Amino‐Induced 2D Cu‐Based Metal–Organic Framework as an Efficient Heterogeneous Catalyst for Aerobic Oxidation of Olefins

“…So far, a variety of new catalysts has been developed in the past decades to achieve the efficient transformation from alkenes into epoxides including both homogeneous catalysts (ruthenium porphyrin, manganese complexes, iron complexes, etc Mn III –polymer catalysts, MOFs, etc …”

Organic carbonates as solvents in macrocyclic Mn(III) salen catalyzed asymmetric epoxidation of non-functionalized olefins

“…Notwithstanding environmental implications; very high catalyst solubility in this solvent also poses challenges in catalyst recyclability [2][3][4]. To make Mn(III) salen catalyst recyclable, strategies like its immobilization on organic polymers [5], inorganic supports [6][7][8], encapsulation in zeolite cavities [9], physical entrapment in siloxane membranes [10], tuneable solubility and multiphase methods have been reported. In the past, the ecologically sensible media have been used, notable among these are water [11][12][13], fluorinated hydrocarbons [14], supercritical CO 2 [15][16][17][18], and ionic liquids [19,20].…”

Olefin epoxidation catalyzed by Schiff base molybdenum (VI) complexes immobilized onto zirconium poly (styrene-phenylvinylphosphonate)-phosphate

“…The microenvironment of ZPS-PVPA for epoxidation, consisted of polystyrene parts which are hydrophobic and the hybrid zirconium phosphonate parts which are hydrophilic and having a self-assembled layered structure with nanometer scale. A large number of polystyrene segments exist in ZPS-PVPA and they are mostly located on the surface of the layers, the interlamellar region and the interlayer surface where they are folding, curl assignment, parallel, cross, even twining, combining with layered zirconium phosphonate-phosphate lead to eventually form different caves, holes, pores, micropores, channels and secondary channels with various sizes and shapes, which may provide a microenvironment effect differing from either pure polystyrene or inorganic supports on catalytic performance for heterogeneous epoxidation [11].…”

“…With these points in mind, a new type of polystyrene-zirconium phosphate composite material (ZPS-PVPA) which has special new characteristics, such as possessing caves, holes, micropores, channels and secondary channels with various sizes and shapes by appropriate modification process of the polystyrene part was prepared. In previous work, we have reported the chiral salen Mn (III) complex axially immobilized onto diamine or polyamine and phenoxyl-modified ZPS-PVPA and their use in catalytic epoxidation, which exhibited great activity and enantioselectivity in the asymmetric epoxidation of unfunctionalized olefins [10][11][12][13]. In order to heterogenize conventional molybdenum catalysts, we have studied the preparation and catalytic activity of a molybdenum (VI)-supported modified ZPS-PVPA.…”

“…4(B), TEM clearly showed that there were many micropores and secondary channels among the layers of the catalyst. These micropores and secondary channels would increase the surface area of the catalysts and provide enough space for substrates to access to the catalytic active sites, which might be one of the main factors of excellent catalytic activities and properties of the heterogeneous catalysts [10,11]. content of PVPA in the copolymer not only because the reactivity of PVPA is less than that of St for the copolymerization, but mainly by means of adjusting the amount of initiator and ratio of PVPA to St. Generally speaking, the main segments of the molecule chain are -(St)m 1 -(PVPA)n-(St)m 2 -(PVPA)n-(St)m 3 -in the copolymer; here the n is usually 1 and seldom more than 2, because the ratio of PVPA to St in the experiment is 1:8 and the content ratio of PVPA to St in the copolymer prepared is in a range of 1:6-9.…”