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Nagel, Ulrich; Albrecht, Jacob

doi:10.1023/a:1019141717606

Cited by 46 publications

(23 citation statements)

References 134 publications

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“…To reduce the dependence on ecologically unsafe chemicals, it is advantageous to carry out reactions in aqueous media [3]. The use of water as a solvent has been accepted for wide range of organic transformation including stereoselective DielseAlder reaction [4], Clasien rearrangement [5], Aldol reaction [6], allylation reaction [7], oxidation including asymmetric epoxydation [8], hydrogenation of alkenes [9], etc. This strategy becomes more attractive if such reactions could be carried out using recyclable catalyst.…”

Section: Introductionmentioning

confidence: 99%

Zn[(l)proline]2 in water: A new easily accessible and recyclable catalytic system for the synthesis of pyrazoles

Kidwai

Jain

Poddar

2011

Journal of Organometallic Chemistry

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Section: Introductionmentioning

confidence: 99%

Zn[(l)proline]2 in water: A new easily accessible and recyclable catalytic system for the synthesis of pyrazoles

Kidwai

Jain

Poddar

2011

Journal of Organometallic Chemistry

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“…[24] Attempts to utilize this ligand in the asymmetric hydrogenation of (Z)-N-acetylamino acrylic and (Z)-N-acetylamino cinnamic acid (AH), which are commonly used as standard substrates, [25] failed owing to the poor activity of the relevant Rh I complex. Interestingly, by benzylation of the OH group (ligand 2-OBn) an active catalyst was obtained.…”

Section: Effects and Preliminary Resultsmentioning

confidence: 99%

The Effect of Internal Hydroxy Groups in Chiral Diphosphane Rhodium(I) Catalysts on the Asymmetric Hydrogenation of Functionalized Olefins

Börner

2001

Eur. J. Inorg. Chem.

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The unique effects of internal hydroxy groups in chiral rhodium(I) diphosphane catalysts on the asymmetric hydrogenation of functionalized olefins are summarized. In the first part, effects caused by the additional functional group on the rate and enantioselectivity of the catalytic reaction with RhI‐diphosphane complexes are shown. For comparison, the results obtained with relevant parent catalysts or complexes bearing alkoxy groups are also considered. Subsequently, mechanistic studies which may explain the rate‐reducing as well as the ee‐enhancing effect of hydroxy groups are discussed in detail. Furthermore, the subtle competitive interplay between the hemilabile behaviour of hydroxy groups and their ability to establish hydrogen bonding within the framework of the ligand or between the ligand and the substrate is shown. Proof is given that conformationally flexible ligands bearing hydroxy groups can respond to varying electronic features of the catalytic centre and the substrate. Finally, the beneficial effect of hydroxy groups on the fine‐tuning of diphosphane catalysts of low performance is demonstrated for some examples. This modification resulted in catalysts which afforded the chiral hydrogenation product in up to 99% ee.

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“…The basic principles of green chemistry have recognized organic synthesis in aqueous medium through replacing utilization of toxic organic solvents [1]. The use of water as a solvent has been accepted for a wide range of organic transformations including stereo selective Diels-Alder reactions [2], Claisen rearrangements [3], aldol reactions [4], allylation reactions [5], oxidations including asymmetric epoxidation [6], and hydrogenation of alkenes [7].…”

Section: Introductionmentioning

confidence: 99%