Pd(II)-Catalyzed Enantioselective C–H Activation of Cyclopropanes
2011 · paper · Chemistry
Reports palladium-catalyzed enantioselective C–H activation of cyclopropanes using newly identified mono-N-protected amino acid ligands. Under mild conditions with diverse organoboron partners, it gives a route to enantioenriched cis-substituted cyclopropanecarboxylic acids.
3 findings
Reference or label "The presence of H2O enhanced the yield (likely by promoting transmetallation)7 without reducing the ee": the '7' is set on the baseline, not as a superscript, and reference 7 is "For stoichiometric metalation of cyclopropyl C–H bonds, see;", which does not concern water or transmetallation. The lead-in of reference 7 also has 'see;' where the other entries have 'see:'.
- p. 2 Body text, Table 2 discussion
(likely by promoting transmetallation)7 without reducing the ee
- p. 4 Reference 7
7. For stoichiometric metalation of cyclopropyl C–H bonds, see;
- p. 2 Results text, para 3 (H2O effect)
(likely by promoting transmetallation)7
- p. 4 Reference 7
For stoichiometric metalation of cyclopropyl C–H bonds
Only the authors can say what is right here.
Judge's note: On the p2 image the '7' after the closing parenthesis is full-size baseline text, unlike every other citation number on the page (e.g. the superscript 13 a few lines above). On the p4 image, ref 7 is a list of stoichiometric cyclopropyl C–H metalation papers, and it is cited appropriately on p1 after 'cyclopropanes.7'. By its own heading it does not support a statement about water promoting transmetallation of the boron reagent; the Suzuki–Miyaura reviews in ref 9 would be a closer fit, but the intended reference (or whether the digit is stray) is for the authors to say. Judged from the reference heading; the cited papers were not read. The 'see;' semicolon in ref 7 is visible on the image (refs 3, 4, 5, 6, 10 use 'see:') and is a separate cosmetic S4 point.
Second check: another model agreed
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Reference or label Reference 3(b): "Angew Chem Int Ed. 2010; 122:7419." gives volume 122 for the International Edition in 2010, while reference 11(b) in the same list gives "Angew Chem Int Ed. 2010; 49:1275."
- p. 4 Reference 3(b)
Int Ed. 2010; 122:7419.
- p. 4 Reference 11(b), same journal and year
Angew Chem Int Ed. 2010; 49:1275.
- p. 4 Reference 3(b)
Int Ed. 2010; 122:7419
- p. 4 Reference 11(b)
Angew Chem Int Ed. 2010; 49:1275
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: that volume 122 is the 2010 volume of the German-language edition of Angewandte Chemie, and what the correct International Edition volume and page of the Renaudat et al. paper are. The inconsistency itself is internal and visible on the p4 image: the same journal title in the same list runs 2005 = 44, 2008 = 47, 2009 = 48, 2010 = 49 (ref 11b), 2011 = 50, so '2010; 122' cannot belong to that title. The corrected volume and page cannot be verified from the files, so this goes to the authors.
Second check: another model agreed
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Wording Text: "coordinating functional groups on the side chain such as an ester (L7), thioether (L8), and ether (L9) gave improved ee, between 65 and 73%; however, the conversion dropped to below 40% in each case"; Table 3 gives L7 "40% yield, 65% ee", which is not below 40% and equals the yields of alkyl ligands L1 and L4 (40%).
- p. 2 Body text, paragraph on amino acid backbone (Table 3 discussion)
conversion dropped to below 40% in each case
- p. 9 Table 3, entry L7, Fmoc-Glu(Ot-Bu)-OH
40% yield, 65% ee
- p. 2 Results text, amino acid backbone para
the conversion dropped to below 40% in each case
Only the authors can say what is right here.
Judge's note: Read Table 3 on the p9 image: L7 40% yield/65% ee, L8 22%/65%, L9 30%/73%; alkyl comparators L1 40%, L2 41%, L4 40%, L5 41%, L6 44%. The text on p2 says 'conversion' while the table reports NMR yield (footnote b); the article gives no separate conversion figures, and conversion cannot be lower than product yield, so the statement does not hold for L7 on the data shown. No explanation found elsewhere in the article. The ee range 65–73% matches the table. Wording imprecision rather than a wrong tabulated number; only the authors can say whether 'at or below 40%' or a different L7 figure was intended.
Second check: another model agreed
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5 minor (typos and the like; most checked by the judge only)
Wording "Recently, Pd-catalyzed asymmetric C–H activation reactions have been demonstrated through the use of a chiral auxiliary1 or chiral ligand.2–6" cites refs 4–6, which the reference list itself heads as Ru-catalyzed atropselective alkylation (4), C–H activation followed by enantioselective addition to olefins (5) and carbenoid/nitrenoid insertion (6), none of them Pd-catalyzed C–H activation.
- p. 1 Introduction, first sentence
Pd-catalyzed asymmetric C–H activation reactions have been demonstrated
- p. 4 Reference 4
For an example of Ru-catalyzed atropselective alkylation
- p. 4 Reference 6
For enantioselective carbenoid and nitrenoid insertion reactions
- p. 1 citation of reference 4
the use of a chiral auxiliary or chiral ligand.
Judge's note: Checked p1 sentence and p4 reference list on the page images. Refs 2 and 3 are Pd work; refs 4–6 are explicitly labelled by the authors as other chemistry ('For an example of Ru-catalyzed...', 'For enantioselective carbenoid and nitrenoid insertion reactions, see'). The headings show they are meant as wider context, so this is loose wording of the sentence rather than a wrong citation. Judged from the reference headings only; the cited works were not read.
Second check: another model agreed
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Typo "a diverse collection of transition metal–mediated transformation have been developed for their synthesis": 'transformation' should be 'transformations'.
- p. 1 Introduction, second paragraph
transformation have been developed for their synthesis
Judge's note: Visible on the p1 image, second paragraph. Singular noun with plural verb 'have' after 'a diverse collection of'.
Second check: none (judge only)
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Typo Misspelling on p. 3: "The chiral cycloproprane products could also undergo further C–H coupling reactions" should read "cyclopropane".
- p. 3 Body text, Table 5 discussion
The chiral cycloproprane
- p. 3
The chiral cycloproprane products could also undergo
- p. 3
The chiral cycloproprane products could also undergo further C–H coupling reactions
Judge's note: I checked the crop image. It shows "cycloproprane" printed in the body text on PDF page 3. The same paragraph spells "cyclopropane" correctly elsewhere, so this is a typo in the published text and not an extraction artefact. The text layer has this spelling only once (main.txt line 127).
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Typo Acknowledgments: "(NRF-2009-352-C00077, postdoctoral fellowship to E.J.Y.) We are grateful to Professor R. Ghadiri": no full stop after the closing parenthesis before the next sentence.
- p. 3 Acknowledgments
fellowship to E.J.Y.) We are grateful
Judge's note: Visible on the p3 image. The only period is the one inside the parenthesis belonging to the initials 'E.J.Y.'; the sentence has no terminating period.
Second check: none (judge only)
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Typo Table 5 footnote c reads "(Second batch) 5mol% Pd(OAc)2"; a space is missing, and it should read "5 mol%" as everywhere else in the footnotes.
- p. 11 Table 5 footnote c
5mol% Pd(OAc)2
Judge's note: The crop shows "5mol%" with no space in the second-batch clause of footnote c, while the first-batch clause of the same footnote and footnotes a and d all print "5 mol%". It is in the page image, not an extraction artefact.
Second check: none (judge only)