Heterogeneous asymmetric epoxidation of cis-allylic alcohols: use of polymer-supported Ti(IV)-catalyst

Karjalainen, Jaana K.; Hormi, Osmo; Sherrington, David C.

doi:10.1016/s0957-4166(98)00188-8

Cited by 28 publications

(8 citation statements)

References 8 publications

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“…Because the methodology in the literature 49,75 involved a rather elaborate workup procedure, the development of a solid-phase analogue would be a valuable improvement. To date, many approaches have been developed to prepare heterogeneous Sharpless-type catalysts for the asymmetric epoxidation of allylic alcohols. ,,− Presently, the advantages of polymer-supported reactive species are widely recognized by organic chemists, and increasing the exploitation of these systems is occurring in both academia and industry . The effective immobilization of asymmetric catalysts, reagents, and auxiliaries is a particularly important methodological target, especially for the metal−complex-based catalysts.…”

Section: 1 Supported Sharpless Systemsmentioning

confidence: 99%

Advances in Homogeneous and Heterogeneous Catalytic Asymmetric Epoxidation

et al. 2005

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Section: 1 Supported Sharpless Systemsmentioning

confidence: 99%

Advances in Homogeneous and Heterogeneous Catalytic Asymmetric Epoxidation

et al. 2005

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“…30 In addition, the enantioselectivity for these reactions has been demonstrated to be sensitive to changes in the ligand structure. 31,32 Earlier work on heterogenizing asymmetric homogeneous catalysts for oxidation involved the incorporation of chiral moieties such as the tartrate-titanium isopropoxide system of Sharpless for epoxidation 33,34 and various cinchona alkaloid derivatives for dihydroxylation onto polymeric supports. 1,[35][36][37] While the enantioselectivities achieved with these catalysts have approached those of the homogeneous catalysts, they suffered upon recycle due to leaching or a lack of stability.…”

Section: Introductionmentioning

confidence: 99%

Polymer-supported salen complexes for heterogeneous asymmetric synthesis: Stability and selectivity

Angelino¹,

Laibinis²

1999

J. Polym. Sci. A Polym. Chem.

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“…However, the preparation of the solids seems to be difficult to reproduce 5. Hormi and co‐workers4c, 4d synthesized insoluble branched/crosslinked poly(tartrate ester)s and investigated their use as optically active ligands in the heterogeneous asymmetric epoxidation of allylic alcohols with titanium tetraisopropoxide and tert ‐butyl hydroperoxide. These gel‐type polymeric ligands swell during the catalytic reaction.…”

Section: Methodsmentioning

confidence: 99%

Asymmetric Epoxidation of Allyl Alcohol on Organic-Inorganic Hybrid Chiral Catalysts Grafted onto the Surface of Silica and in the Mesopores of MCM-41

et al. 2002

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Asymmetric epoxidation of allylic alcohols is an important reaction in synthetic organic chemistry. [1] Sharpless and Katsuki [2] have provided an excellent homogeneous catalytic system for this reaction which consists of titanium tetraisopropoxide and a chiral dialkyl tartrate. Heterogeneous systems have tremendous advantages over homogeneous catalytic systems. [3] One of the most attractive advantages is the easy separation of the product from the catalyst without tedious experimental work-up.Different approaches have been used in the preparation of heterogeneous Sharpless-type catalytic systems for the asymmetric epoxidation of allylic alcohols. An early attempt to develop a polymer-supported system employed a single tartrate ester unit bound to a polystyrene resin; [4a] in this case, the chiral induction was only modest (ca. 50 ± 60 % ee). Choudary et al. [4b] reported the asymmetric epoxidation of allylic alcohols with a heterogeneous titanium-pillared montmorillonite catalyst in the presence of chiral tartrate ester. However, the preparation of the solids seems to be difficult to reproduce. [5] Hormi and co-workers [4c, 4d] synthesized insoluble branched/crosslinked poly(tartrate ester)s and investigated their use as optically active ligands in the heterogeneous asymmetric epoxidation of allylic alcohols with titanium tetraisopropoxide and tert-butyl hydroperoxide. These geltype polymeric ligands swell during the catalytic reaction. Basset and co-workers [4e] reported silica-supported tantalum catalysts for the enantioselective epoxidation of allylic alcohols in the presence of chiral tartrate derivatives. Their result is comparable to that obtained in the homogeneous Sharpless reaction. However, the organometallic tantalum compound used in the synthesis is not easy to prepare. [6] The preparation of organic ± inorganic hybrid materials is of growing interest. [7, 8] In contrast to organic polymers, organic ± inorganic hybrid materials do not swell or dissolve in organic solvents, and have many advantages over most organic polymers because of their superior mechanical and thermal stabilities. Moreover, any leaching could be avoided as the organic moieties are covalently attached to the inorganic supports. For hybrid materials, the design and synthesis of chiral catalytic materials [8] with high enantioselectivities are especially attractive. [8c±e] Highly efficient and enantioselective transition metal complexes have been reported in the literature. The design and synthesis of chiral hybrids with activity and enantioselectivity similar to that of homogeneous catalysts remain a challenge. Few reports have appeared on the synthesis of organic ± inorganic hybrid chiral materials and on their use as heterogeneous catalysts in enantioselective reactions. [8c±e] We report herein the synthesis of organic ± inorganic hybrid chiral materials by grafting a chiral tartaric acid derivative onto the surface of silica and in the mesopores of MCM-41 material (Scheme 1 b), and provide the first example of their su...

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Heterogeneous asymmetric epoxidation of cis-allylic alcohols: use of polymer-supported Ti(IV)-catalyst

Cited by 28 publications

References 8 publications

Advances in Homogeneous and Heterogeneous Catalytic Asymmetric Epoxidation

Advances in Homogeneous and Heterogeneous Catalytic Asymmetric Epoxidation

Polymer-supported salen complexes for heterogeneous asymmetric synthesis: Stability and selectivity

Asymmetric Epoxidation of Allyl Alcohol on Organic-Inorganic Hybrid Chiral Catalysts Grafted onto the Surface of Silica and in the Mesopores of MCM-41

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