Lewis Acid-Catalyzed Enantioselective Hydroxylation Reactions of Oxindoles and β-Keto Esters Using DBFOX Ligand

Ishimaru, Takehisa; Shibata, Norio; Nagai, Jun; Nakamura, Shuichi; Toru, Takeshi; Kanemasa, Shuji

doi:10.1021/ja0668825

Cited by 255 publications

(70 citation statements)

References 27 publications

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“…13 Thus owing to the significance of the oxindole structural motif, the development of catalytic methods for the synthesis of oxindoles bearing a C-3 hydroxy quaternary centre is highly desirable.…”

Section: Graphical Abstractmentioning

confidence: 81%

A catalytic, mild and efficient protocol for the C-3 aerial hydroxylation of oxindoles

Buckley

D.‐R.

2013

Tetrahedron Letters

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A catalytic, mild and efficient protocol for the C-3 aerial hydroxylation of oxindoles his item ws sumitted to voughorough niversity9s snstitutionl epository y theGn uthorF Citation: fguviD fFF nd pix ¡ exhi hFEFD fFD PHIQF e tlytiD mild nd effiient protool for the gEQ eril hydroxyltion of oxindolesF etrE hedron vettersD SR @VAD ppFVRQEVRTF Additional Information:• xysgiX this is the uthor9s version of work tht ws epted for pulition in etrhedron vettersF ghnges resulting from the pulishE ing proessD suh s peer reviewD editingD orretionsD struturl formtE tingD nd other qulity ontrol mehnisms my not e refleted in this doumentF ghnges my hve een mde to this work sine it ws suE mitted for pulitionF e definitive version ws susequently pulished tX httpXGGdxFdoiForgGIHFIHITGjFtetletFPHIPFIIFHVQ Methods for functionalization of the oxindole nucleus are of significant value in medicinal chemistry and natural product synthesis.1 Due to their unprecedented structural diversity, biological activity and structural challenge, oxindoles continue to attract the interest of chemists and biologists alike. For example, the convolutamydines, 2 and the 3-hydroxywelwitindolinones are part of a growing list of biologically active 3-hydroxyoxindoles (Figure 1).3 3-Hydroxyoxindoles with a quaternary benzylic centre are a useful class of compounds also found in several drug candidates, including the potent, orally active growth hormone There are a number of reports on the enantioselective formation of quaternary carbon centers at the 3-position of oxindoles.6 For example, Hartwig first reported the palladiumcatalysed synthesis of oxindoles by amide α-arylation with ees of up to 67%; 7 This was later improved upon by Kündig using modified N-heterocyclic carbenes 8 and Marsden has reported several methods for the synthesis of 3-hydroxy-and 3-aminooxindoles. 9Copper-mediated processes have also recently been employed to prepare quaternary C-3 oxindoles by both the Kündig 10 and Taylor groups.11 Also of note are the recent reports by Franz,12 who has reported the asymmetric direct addition of nucleophiles to isatins using chiral Lewis acids, and Shibata and Toru who have reported the asymmetric C-3 hydroxylation of oxindoles also using chiral Lewis acids, with an oxaziridine as the stoicheiometric oxidant. 13 Thus owing to the significance of the oxindole structural motif, the development of catalytic methods for the synthesis of oxindoles bearing a C-3 hydroxy quaternary centre is highly desirable.Gassman and Halweg reported the air oxidation of oxindoles to isatins (Scheme 1) through treatment of 3-methylthiooxindoles with a strong stoicheiometric base and air; strict anhydrous conditions were required in order to prevent degradation of the isatin to the corresponding anthranilic acid.14 We also noted the recent report from Curran and co-workers, 15 where the attempted removal of the trimethylsilyl (TMS) group from 1 resulted in 3-hydroxy-1,3-dihydroindol-2-one 2 being the sole product of the reaction (Scheme 2). Careful investigation of...

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Section: Graphical Abstractmentioning

confidence: 81%

A catalytic, mild and efficient protocol for the C-3 aerial hydroxylation of oxindoles

Buckley

D.‐R.

2013

Tetrahedron Letters

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“…1). 4, 5 Previously, we reported the use of dicationic (diphosphine) palladium(II) catalysts for highly enantioselective addition of aromatic amines to Michael acceptors containing 1,3-dicarbonyl chelating substrates. 6 Herein, we will demonstrate that these catalysts can also be used to effect enantioselective hydroxylation of several cyclic and acyclic b-ketoesters (Fig.…”

Section: Q1mentioning

confidence: 99%

“…Indeed, this corresponds to the stereochemistry of predominant enantiomers obtained for 3a 15 and 3c. 4 Dicationic BINAP-palladium complex 1 catalyses highly enantioselective a-hydroxylation of cyclic and acyclic b-ketoesters, using DMD as a 'clean' oxidant. Unprecedented enantioselectivities of up to 98% can be obtained with cyclic substrates and 88% for acyclic substrates.…”

Section: Q1mentioning

confidence: 99%

Palladium-catalysed enantioselective α-hydroxylation of β-ketoesters

2009

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Highly enantioselective a-hydroxylation of cyclic and acyclic 1,3-ketoesters can be achieved with up to 98% ee using a dicationic palladium(II) catalyst and dimethyldioxirane as oxidant.Please check this proof carefully. Our staff will not read it in detail after you have returned it. Translation errors between word-processor files and typesetting systems can occur so the whole proof needs to be read. Please pay particular attention to: tabulated material; equations; numerical data; figures and graphics; and references. If you have not already indicated the corresponding author(s) please mark their name(s) with an asterisk. Please e-mail a list of corrections or the PDF with electronic notes attached --do not change the text within the PDF file or send a revised manuscript.Please bear in mind that minor layout improvements, e.g. in line breaking, table widths and graphic placement, are routinely applied to the final version.Please note that, in the typefaces we use, an italic vee looks like this: n, and a Greek nu looks like this: n.

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“…There are few methodologies for the synthesis of chiral 3-hydroxy-3-methyl-2-oxindoles in the literature, and the number of catalytic enantioselective examples is scarce. For example, the asymmetric oxidation of 3-methylindolin-2-one has been described for the synthesis of such compounds [25][26][27]. However, the most direct and versatile methodology is the enantioselective nucleophilic addition of organometallic reagents to isatins (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%