Retention of Regiochemistry of Allylic Esters in Palladium-Catalyzed Allylic Alkylation in the Presence of a MOP Ligand

Hayashi, Tamio; Kawatsura, Motoi; Uozumi, Yasuhiro

doi:10.1021/ja973150r

Cited by 151 publications

(65 citation statements)

References 18 publications

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“…[1j, 185] In addition, Pfaltz and co-workers demonstrated that the regio-and enantioselectivity of allylic alkylations can be tuned by systematic modification of the electronic and steric properties of the ligands in the palladium catalysts. By using the new type of chiral oxazoline ligands L171 and L172, good regio-and enantioselectivitities were observed in the reaction with 3-(1'-naphthyl)-1-propen-3-yl acetate (94 e) or 85 d. [186,187] However, low regioselectivitities were observed for other substrates with R = 2-naphthyl, phenyl, methyl, or (CH 3 ) 2 C=CH.…”

Section: Nucleophilesmentioning

confidence: 99%

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

2007

Angew Chem Int Ed

1,361

431

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Metal-catalyzed enantioselective allylation, which involves the substitution of allylic metal intermediates with a diverse range of different nucleophiles or S(N)2'-type allylic substitution, leads to the formation of C-H, -C, -O, -N, -S, and other bonds with very high levels of asymmetric induction. The reaction may tolerate a broad range of functional groups and has been applied successfully to the synthesis of many natural products and new chiral compounds.

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Section: Nucleophilesmentioning

confidence: 99%

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

2007

Angew Chem Int Ed

1,361

431

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“…1). Although, regiochemistry has often been determined on the basis of substitution patterns of the termini of the allyl, Hayashi et al have recently shown that the regiochemistry of nucleophilic attack in some cases can be determined by differences in trans influence of the phosphine and the other ligand [20].…”

Section: In Memoriam Professor Luigi M Venanzimentioning

confidence: 99%

Rearrangements in Allylpalladium Complexes with Hemilabile Chelating Ligands

Faller¹,

Stokes‐Huby²,

Albrizzio³

2001

HCA

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In memoriam Professor Luigi M. VenanziIn addition to h 3 -to h 1 -allyl rearrangement, h 2 -to h 1 -chelating-ligand rearrangements can affect the dynamic properties in allylpalladium complexes containing hemilabile ligands. These rearrangements have the potential of altering stereochemistry, which can ultimately affect the stereochemistry and regiochemistry of reactions upon the allyl group, e.g., allylic alkylation. Apparent rotation of an h 3 -allyl in four-coordinate Pd IIcomplexes can be the result of ligand exchange or intramolecular processes. NMR Studies indicate that the effects of h 2 -to h 1 -chelating-ligand stereochemistry and rearrangements may be hidden or subtle, and both intraand intermolecular processes may be important.Introduction. ± The synthetic utility of transition-metal-catalyzed alkylations involving allyl intermediates has been shown to be effective for the regio-and stereocontrolled formation of CÀC bonds over the past thirty years [1] [2]. Asymmetric variants have been developed more recently [3]. Early work focused on the use of bisphosphane ligands, such as chiraphos [3], where C 2 -symmetric ligands were considered to have special advantages [4]. More recently, however, some of the most impressive enantioselectivities have been obtained with asymmetric P,N ligands, e.g., phosphinoaryloxazolines [5 ± 13]. In general, the complexes show dynamic NMR spectra, which indicate that the complexes are rearranging rapidly. The stereodynamics in these systems can be important in enantioselective allylic alkylations and has been reviewed recently [14], but many of the principles were established previously [3] [15 ± 19]. A number of rearrangements are possible that can affect the geometry. In earlier work, there was a tendency to overemphasize the importance of a C 2 -symmetric ligand for obtaining high levels of asymmetric induction. However, the excellent levels of enantioselectivity obtained with P,N ligands has demonstrated that asymmetric bidentate ligands can be as effective as, if not superior to, C 2 -symmetric ligands [5 ± 13].With a C 2 -symmetric ligand, such as chiraphos [3], a rotation of the allyl group or the ligand will yield an equivalent structure; hence, the presence or absence of a rotation mechanism may be irrelevant. With a non-C 2 -symmetric ligand, however, a different isomer will be produced and this has the potential to have significant consequences with regard to the resulting stereochemistry of the allyl product (see Fig. 1). Although, regiochemistry has often been determined on the basis of substitution patterns of the termini of the allyl, Hayashi et al. have recently shown that the regiochemistry of nucleophilic attack in some cases can be determined by differences in trans influence of the phosphine and the other ligand [20].

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“…[20] This effect is also observed when MOP is used. [21] With monodentate diamidophosphites [22] or 9-PBN [23] the ee obtained in the benchmark reaction can be 97 %. When it is possible to compare the results of palladium catalysts stabilized by a bidentate or two monodentate phosphanes containing the same substituents, the rate observed is usually faster in the systems that contain monodentate ligands, whereas the selectivity is similar in both cases.…”

Section: Introductionmentioning

confidence: 99%

Better Performance of Monodentate P‐Stereogenic Phosphanes Compared to Bidentate Analogues in Pd‐Catalyzed Asymmetric Allylic Alkylations

et al. 2010

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The cationic allylpalladium complexes 3a-3f, 4a, 4e, 5e of type [Pd(η 3 -2-Me-C 3 H 4 )P 2 ]PF 6 were synthesized using a group of monodentate P-stereogenic phosphanes, P=PPhRRЈ (a-f) and diphosphanes (PhRPCH 2 ) 2 (1a, 1e) or PhRPCH 2 Si(Me) 2 CH 2 PPhR (2e). The analogous cationic complexes with the disubstituted allyl group (η 3 -1,3-Ph 2 -C 3 H 3 ) and monodentate phosphanes were not isolated as stable solids; only [PdCl(η 3 -1,3-Ph 2 -C 3 H 3 )P] (6a, 6d) were obtained. Palladium allyl complexes were screened as precatalysts in the allylic substitution of rac-3-acetoxy-1,3-diphenyl-1-propene (I) and (E)-3-acetoxy-1-phenyl-1-propene (III) with dimethyl malonate as the nucleophile. The various catalytic precursors showed a wide range of activity and selectivity. The bismonodentate phosphane complexes 3 are more active

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Retention of Regiochemistry of Allylic Esters in Palladium-Catalyzed Allylic Alkylation in the Presence of a MOP Ligand

Cited by 151 publications

References 18 publications

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

Rearrangements in Allylpalladium Complexes with Hemilabile Chelating Ligands

Better Performance of Monodentate P‐Stereogenic Phosphanes Compared to Bidentate Analogues in Pd‐Catalyzed Asymmetric Allylic Alkylations

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