Optically Active Phospholanes as Substituents on Ferrocene and Chromium‐Arene Complexes

Braun, Wolfgang; Calmuschi, Beatrice; Haberland, Jürgen; Hummel, Werner; Liese, Andreas; Nickel, Thomas; Stelzer, O.; Salzer, Albrecht

doi:10.1002/ejic.200300685

Cited by 25 publications

(22 citation statements)

References 41 publications

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“…At first one carbonyl group is reduced to yield (S)-5-hydroxyhexane-2-one 5 followed by a subsequent reduction to the product (S,S)-2,5-hexanediol 2c. The dialcohol is an intermediate for the synthesis of the complementary isomer of the DuPhos-ligand, which is used in the asymmetric hydrogenation of a,b-unsaturated amino acids (Braun et al, 2004).…”

Section: Two-step Reduction Of 25-hexanedionementioning

confidence: 99%

Overcoming the thermodynamic limitation in asymmetric hydrogen transfer reactions catalyzed by whole cells

Goldberg

Edegger

Kroutil

et al. 2006

Biotech & Bioengineering

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Whole lyophilized cells of an Escherichia coli overexpressing the alcohol dehydrogenase (ADH-'A') from Rhodococcus ruber DSM 44541 were used for the asymmetric reduction of ketones to secondary alcohols. The recycling of the required nicotinamide cofactor (NADH) was achieved in a coupled-substrate process. In the course of the reaction the ketone is reduced to the alcohol and the hydrogen donor 2-propanol is oxidized to acetone by one enzyme. This leads to a thermodynamic equilibrium between all four components determining the maximum achievable conversion. To overcome this limitation an in situ product removal technique (ISPR) for the application with whole cells was developed. In this method the most volatile compound is separated from the reaction vessel by an air flow resulting in a shift of the equilibrium towards the desired secondary alcohol. The so-called stripping process represents a simple and efficient method to overcome the thermodynamic limitation in biocatalytic reactions. Employing this method, the conversion of selected biotransformations was increased up to completeness.

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Section: Two-step Reduction Of 25-hexanedionementioning

confidence: 99%

Overcoming the thermodynamic limitation in asymmetric hydrogen transfer reactions catalyzed by whole cells

Goldberg

Edegger

Kroutil

et al. 2006

Biotech & Bioengineering

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“…94,140,199−203 The introduction of a nucleophile at the α carbon is usually achieved by starting from the corresponding acetate, which is quantitatively accessible upon treatment of the tertiary amine with excess acetic anhydride or, more conveniently, directly from Organometallics Review dx.doi.org/10.1021/om400564x | Organometallics XXXX, XXX, XXX−XXX the amine in glacial acetic acid. In this way, the NMe 2 moiety has been replaced by ammonia and primary and secondary amines 74,128,129,131,134,135,137,148,155,158,197,204,205 as well as phosphines, 74,138,147,157,172,181,183,184,193,196,198,206 including heterocyclic species, 87,128,129,140,141,146,154,179,184,185,190,207−210 azides for 1,3-dipolar cycloadditions, 166 carbon nucleophiles, 84,85,143 alcohols, 74,76 and thioles 147,161,…”

Section: ■ Ortho-directed Metalationmentioning

confidence: 99%

Selective Syntheses of Planar-Chiral Ferrocenes

2013

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Planar-chiral ferrocenes are widely applied in catalytic asymmetric transformations in scientific research as well as in industry. A plethora of different methodologies have been developed to access these molecules with a high degree of regio- and stereoselectivity. The aim of this contribution is to give a comprehensive overview of this topic. The synthesis of 1,2- and 1,3-substituted ferrocenes by electrophilic aromatic substitution, ortho-directed metalation, kinetic resolution, and desymmetrization is discussed. Advantages and disadvantages are highlighted.

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“…The group of Salzer has recently reported phospholanes 54-56 based on chiral half-sandwich complexes [79]. These were obtained by treatment of the appropriately substituted complex with a secondary phospholane, itself accessed via the cyclic sulfate or dimesylate and PH 3 .…”

Section: Other Phospholane-containing Ligandsmentioning

confidence: 99%

Enantioselective Hydrogenation: Phospholane Ligands

Cobley¹,

Moran²

2006

The Handbook of Homogeneous Hydrogenation

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The ability to efficiently synthesize enantiomerically enriched materials is of key importance to the pharmaceutical, flavor and fragrance, animal health, agrochemicals, and functional materials industries [1]. An enantiomeric catalytic approach potentially offers a cost-effective and environmentally responsible solution, and the assessment of chiral technologies applied to date shows enantioselective hydrogenation to be one of the most industrially applicable [2]. This is not least due to the ability to systematically modify chiral ligands, within an appropriate catalyst system, to obtain the desired reactivity and selectivity. With respect to this, phosphorus(III)-based ligands have proven to be the most effective.Amongst the hundreds of chiral phosphorus-based ligands developed since the seminal studies of Knowles and Horner [3], only a select few ligand families have had a revolutionary impact on the field. The highly modular chiral C 2 -symmetric phospholane ligands (DuPhos TM and BPE), developed by Burk and coworkers at DuPont, are one such example. As a result, much effort has been directed towards building on this breakthrough discovery and extending both the design and application of this ligand class.In this chapter, we review the growing family of phospholane-based chiral ligands, and specifically examine their applications in the field of enantioselective hydrogenation. In general, this ligand class has found its broadest applicability in the reduction of prochiral olefins and, to a significantly lesser extent, ketones and imines; this is reflected in the composition of the chapter. Several analogous phosphacycle systems have also been included, where appropriate.Whilst trying to be comprehensive, we have also intended to introduce a strong applied flavor to this summary. In the industrial case, catalyst performance is critically judged on overall efficiency, namely catalyst productivity and activity as well as enantioselectivity. As a result, turnover numbers (TONs) and turnover frequencies (TOFs) have been included or calculated whenever possible and meaningful. 773The Handbook of Homogeneous Hydrogenation. Edited by J. G. de Vries and C. J. Elsevier

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Optically Active Phospholanes as Substituents on Ferrocene and Chromium‐Arene Complexes

Cited by 25 publications

References 41 publications

Overcoming the thermodynamic limitation in asymmetric hydrogen transfer reactions catalyzed by whole cells

Overcoming the thermodynamic limitation in asymmetric hydrogen transfer reactions catalyzed by whole cells

Selective Syntheses of Planar-Chiral Ferrocenes

Enantioselective Hydrogenation: Phospholane Ligands

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