Fluorous biphasic hydrolytic kinetic resolution of terminal epoxides

Shepperson, Ian; Cavazzini, Marco; Pozzi, Gianluca; Quici, Silvio

doi:10.1016/j.jfluchem.2003.07.008

Cited by 32 publications

(15 citation statements)

References 23 publications

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“…Inorganic supports including silica [42][43][44] and zeolite [45] and liquid-immobilization methods, such as the fluorous biphasic system (FBS) [46] and ionic liquids, [47] were also applied to investigate recyclable HKR catalysts. Interestingly, kinetic studies of the HKR reactions with the homogeneous Co-salen catalyst 2 indicated a second-order dependence of the reaction rates on the Co-salen species; this dependence strongly supports a cooperative bimetallic mechanism for the ring-opening step.…”

Section: Introductionmentioning

confidence: 99%

Poly(styrene)‐Supported Co–Salen Complexes as Efficient Recyclable Catalysts for the Hydrolytic Kinetic Resolution of Epichlorohydrin

Zheng

Jones

Weck

2005

Chemistry A European J

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Here we describe an unprecedented synthetic approach to poly(styrene)-supported chiral salen ligands by the free radical polymerization of an unsymmetrical styryl-substituted salen monomer (H2salen = bis(salicylidene)ethylenediamine). The new method allows for the attachment of salen moieties to the polymer main chain in a flexible, pendant fashion, avoiding grafting reactions that often introduce ill-defined species on the polymers. Moreover, the loading of the salen is controlled by the copolymerization of the styryl-substituted salen monomer with styrene in different ratios. The polymeric salen ligands are metallated with cobalt(II) acetate to afford the corresponding supported Co-salen complexes, which are used in the hydrolytic kinetic resolution of racemic epichlorohydrin, exhibiting high reactivity and enantioselectivity. Remarkably, the copolymer-supported Co-salen complexes showed a better catalytic performance (>99 % ee, 54 % conversion, one hour) in comparison to the homopolymeric analogues and the small molecule Co-salen complex. The soluble poly(styrene)-supported catalysts were recovered by precipitation after the catalytic reactions and were recycled three times to afford almost identical enantiomeric excesses as the first run, with slightly reduced reaction rates.

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Section: Introductionmentioning

confidence: 99%

Poly(styrene)‐Supported Co–Salen Complexes as Efficient Recyclable Catalysts for the Hydrolytic Kinetic Resolution of Epichlorohydrin

Zheng

Jones

Weck

2005

Chemistry A European J

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“…In another context, Pozzi et al. have demonstrated that the hydrolytic KR of epoxides was feasible under fluorous biphasic conditions provided that proper highly‐fluorinated ligands were selected 179. In this study, it was shown that the nature of the counter anion had a dramatic effect on the catalytic activity of heavily fluorinated chiral (salen) cobalt(III) complexes such as 58 .…”

Section: Kinetic Resolution Of Epoxidesmentioning

confidence: 64%

Catalytic Non‐Enzymatic Kinetic Resolution

Pellissier

2011

Adv Synth Catal

318

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While tremendous advances have been made in asymmetric synthesis, the resolution of racemates is still the most important industrial approach to the synthesis of chiral compounds. The use of enzymes for the kinetic resolution (KR) of racemic substrates to afford enantiopure compounds in high enantioselectivity and good yield has long been a popular strategy in synthesis. However, transition metal-mediated and more recently organocatalyzed KRs have gained popularity within the synthetic community over the last two decades due to the progress made in the development of chiral catalysts for asymmetric reactions. Many catalytic non-enzymatic procedures have been developed providing high enantioselectivity and yield for both products and recovered starting materials. Indeed, the non-enzymatic KR of racemic compounds based on the use of a chiral catalyst is presently an area of great importance in asymmetric organic synthesis. The goal of this review is to provide an update on the principal developments of catalytic non-enzymatic KR covering the literature since 2004. This review is subdivided into seven sections, according to the different types of compounds that have been resolved through catalytic non-enzymatic KR, such as alcohols,

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“…1 H NMR spectra were recorded at 300 MHz on a Varian INOVA 300 spectrometer or, where stated, at 270 MHz on a Jeol JNM-GX270 FT spectrometer. 13 C NMR spectra were recorded at 75 MHz (Varian). Chemical shifts are reported as d-values in ppm relative to tetramethylsilane (TMS).…”

Section: Generalmentioning

confidence: 99%

“…[1][2][3] Synthetic methods based on metal(salen) complexes have been developed for both asymmetric epoxidation (AE) of alkenes [2][3][4] and the asymmetric ringopening of epoxides. [5][6][7][8][9][10][11][12][13] We have specifically investigated Cr(salen)-mediated AE, [14][15][16][17][18][19][20][21][22][23] as have others. [24][25][26][27][28] We found it intriguing that the Cr-system shows high enantioselectivity for the conversion of trans-1,2-disubstituted alkenes (trans-alkenes henceforth) in contrast to almost all known Mn(salen) systems.…”

Section: Introductionmentioning

confidence: 99%