New chiral ligands, pyrrolidinyl- and 2-azanorbornyl- phosphinooxazolidines for palladium-catalyzed asymmetric allylation

Okuyama, Yuko; Nakano, Hiroto; Hongo, Hiroshi

doi:10.1016/s0957-4166(00)00049-5

Cited by 64 publications

(22 citation statements)

References 16 publications

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“…[69,70] On the other hand, the use of silyl-protected α,α-diarylprolinol catalysts, developed in his group, resulted in preparative problems, as separation of catalyst and product could only be achieved after reduction of the aldehyde, so this route was not pursued any further, once it became apparent that catalyst 12 would not provide improved stereoselectivity in relation to proline. In contrast, catalyst 13 allowed the isolation of product 4b in 52 % yield, displaying the highest reactivity of all catalysts tested in the reaction, although the selectivity remained somewhat below that achieved with -proline.…”

Section: Screening Of Catalystsmentioning

confidence: 98%

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Direct Asymmetric α‐Sulfamidation of α‐Branched Aldehydes: A Novel Approach to Enamine Catalysis

Vogt¹,

Baumann²,

Nieger³

et al. 2006

Eur J Org Chem

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Proline‐catalysed reactions between α‐branched aldehydes and sulfonyl azides provide scalemic configurationally stabilised α‐sulfamidated products with ee values of up to 86 %. The reactions can also be carried out in a one‐pot fashion, with catalyst, aldehyde, sulfonyl chloride and sodium azide. The proposed mechanism differs fundamentally from the mechanistic model usually ascribed to enamine catalysis, containing as a key step the diastereoselective cycloaddition of the azide to an enamine formed in situ. The products obtained in the reaction can be converted into the corresponding unnatural amino acids in two additional steps.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Screening Of Catalystsmentioning

confidence: 98%

“…[62,70,78] In the present case, this would result in the formation of triazenes or azide transfer, Scheme 2. Proposed mechanism for the pyrrolidine-catalysed α-sulfamidation of α-branched aldehydes.…”

Section: Mechanistic Considerationsmentioning

confidence: 99%

Direct Asymmetric α‐Sulfamidation of α‐Branched Aldehydes: A Novel Approach to Enamine Catalysis

Vogt¹,

Baumann²,

Nieger³

et al. 2006

Eur J Org Chem

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“…28 12 can be used as a chiral ligand for asymmetric transfer hydrogenation of ketones, 28 and as a starting material for ring-closure reactions. 19,20 The synthesis of heterocycle 14 started from the pchlorophenyl isothiocyanate adduct of 12. Treatment of thiourea 13 with ethanolic hydrogen chloride under reflux provided thiazolidine 14 (Scheme 4).…”

Section: Methodsmentioning

confidence: 99%

Ring closure reactions of bicyclic prolinol and prolin ester enantiomers

Palkó¹,

Molnár²,

Kivelä³

et al. 2009

Arkivoc

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Starting from the of bicyclic proline ester, ethyl exo-2-azabicyclo[2.2.1]heptane-3-carboxylate (+)-5 several hydantoines and thiohydantoines were prepared by acidic ring closure of the corresponding urea or thiourea derivatives. Enantiomer (-)-5 was reduced to 2-azanorbornylmethanol 12, which was transformed to 5,8-methanooxazolo-and thiazolo[3,4-a]pyridine derivatives. The structures, stereochemistry and relative configurations of the synthesized compounds were proved by NMR.

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“…[44] Similar ligands 119 and 120 which contain the oxazolidine ring as part of a bi-or tricyclic structure were developed by Nakano. [45] These ligands were tested in the palladium-catalysed allylic alkylation of 1,3-diphenyl-2-propenyl acetate (15) where all except ligand 120 afforded the product 16 in excellent yields and enantioselectivities, Table 8, entries 1 ±5.…”

Section: Oxazolidine N Donormentioning

confidence: 99%

The Development of Bidentate P,N Ligands for Asymmetric Catalysis

2004

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In this review, an attempt is made to systemise the ro √ le which bidentate phosphinamine (P,N) ligands play in asymmetric catalysis. The ligands will be classified, not by the reaction to which their metal complexes have been applied, but by the nature of their donor atoms. In this manner the development of ligand architectural design can be more easily monitored. The asymmetric transformations to which metal complexes of these ligands have been applied include among others, palladium-catalysed allylic substitutions, copper-catalysed 1,4-additions to enones and rhodiumcatalysed hydroboration of vinylarenes. Excellent enantioselectivities, regioselectivities and reactivities have been achieved in each of these processes.

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New chiral ligands, pyrrolidinyl- and 2-azanorbornyl- phosphinooxazolidines for palladium-catalyzed asymmetric allylation

Cited by 64 publications

References 16 publications

Direct Asymmetric α‐Sulfamidation of α‐Branched Aldehydes: A Novel Approach to Enamine Catalysis

Direct Asymmetric α‐Sulfamidation of α‐Branched Aldehydes: A Novel Approach to Enamine Catalysis

Ring closure reactions of bicyclic prolinol and prolin ester enantiomers

The Development of Bidentate P,N Ligands for Asymmetric Catalysis

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