Photoredox Catalysis: A Mild, Operationally Simple Approach to the Synthesis of α-Trifluoromethyl Carbonyl Compounds
Angewandte Chemie, 2011 · paper · Chemistry
Describes a room-temperature photoredox method to add trifluoromethyl groups next to carbonyls via enolsilanes. A one-pot protocol extends it to fluoroalkylation of ketones, esters, and amides without isolating the enolsilane intermediates.
3 findings
Reference or label Table 2 ("Trifluoromethylation of enolsilanes: ketone scope") carries the reaction scheme of Table 3: an OTBS "silylketene acetal", "No photocatalyst", "DMF, 23 °C", product "α-CF3 ester/amide". This contradicts the table's title, its ketone products, footnote "[a] ... SiR3 = TIPS unless otherwise noted" and the text, which describes Table 2 as the Ru photoredox protocol.
- p. 7 Table 2, header scheme
No photocatalyst
- p. 5 Table 2, header scheme labels
silylketene acetal
- p. 8 Table 2, footnote [a]
SiR3 = TIPS unless otherwise noted
- p. 8 Table 2, header scheme, product label
ester/amide
Judge's note: Compared the page 8 and page 9 images: the header scheme above the Table 2 entries is the same graphic as the Table 3 header (OTBS, X, R', R'', silylketene acetal, No photocatalyst, DMF 23 °C, α-CF3 ester/amide). Every Table 2 product is a ketone. The text on page 2 says Table 2 uses 'this new photoredox trifluoromethylation protocol' with the optimal conditions of 0.5 mol% [Ru(bpy)3Cl2], THF-H2O and iPr2NEt, and Table 1 entry 3 gives <1% yield with no photocatalyst. The catalyst-free result is described on page 3 only for the ester and amide substrates of Table 3. No statement in the article explains the header. It may have been introduced when the author manuscript was assembled, but it is wrong in this PDF. The yields themselves are not affected, so this is a wrong label.
Second check: another model agreed
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Reference or label Table 1: the scheme above the table gives the conditions as "0.5 mol% 1•H2O / iPr2EtN, H2O / THF, 23 °C", but the column "Variation from above conditions" lists entry 1 as "none" (35%), and the footnotes ("THF used instead of DMF.", "Instead of Et3N.") and the text ("1.5 equivalents of Et3N in DMF (entry 1, 35% yield)") define the baseline as Et3N in DMF without water.
- p. 7 Table 1, scheme above the table
THF, 23 °C
- p. 7 Table 1, column header
Variation from above conditions
- p. 7 Table 1, footnotes
THF used instead of DMF.
- p. 2 paragraph 'As shown in Table 1'
presence of 1.5 equivalents of Et3N in DMF (entry 1, 35% yield)
Judge's note: Viewed the page 7 image and the crop. The scheme shows the optimised conditions (iPr2EtN, H2O, THF), which are those of entry 8 (94%). Entries 5-8 add H2O, THF and iPr2NEt as variations, so the baseline the column refers to is not the one drawn. The page 2 text confirms entry 1 was Et3N in DMF. Nothing in the article explains the mismatch. The data are fine; the scheme or the column header is mislabelled.
Second check: another model agreed
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Reference or label Table 3 footnotes are labelled [a], [b], [a]: the third, "[a]In MeCN.", should be [c], which entry 3 cites ("3: 74%[b,c]") and which is otherwise undefined.
- p. 9 Table 3, third footnote
[a]In MeCN.
- p. 9 Table 3, entry 3
3: 74%[b,c]
- p. 9 Table 3, first footnote
[a]Yield of isolated products.
- p. 9 Table 3 footnotes
In MeCN.
Judge's note: Viewed the page 9 image. Footnotes as printed: "[a]Yield of isolated products.", "[b]0.5 mol% 1·H2O, Et3N, isoamyl alcohol employed.", "[a]In MeCN." Entry 3 carries [b,c] and there is no footnote [c]. The label is in the page image, so it is not an extraction artefact. The fix is evident: relabel the third footnote [c].
Second check: another model agreed
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14 minor (typos and the like; most checked by the judge only)
Wording Table 4 is titled "one-pot a-perfluoroalkylation of carbonyl compounds" and its scheme labels the product "α-CF3 carbonyl", but entry 6 is an "α-difluoro diester" (CF2CO2Et, not a perfluoroalkyl group), which the text itself separates: "underwent perfluoroalkylation (n-propyl and isopropyl) and difluoroalkylation".
- p. 10 Table 4 title
one-pot a-perfluoroalkylation of carbonyl compounds
- p. 10 Table 4, entry 6
6: α-difluoro diester
- p. 3 Paragraph on Table 4
underwent perfluoroalkylation (n-propyl and isopropyl) and difluoroalkylation
Judge's note: Viewed the page 10 image and read the page 3 text. Entries 1-5 (CF3, n-C3F7, i-C3F7) fit "perfluoroalkylation"; entry 6 does not, and the text uses the broader "α-fluoroalkylations" for the set. The title is a loose umbrella term. This is a minor wording point where the authors may prefer to keep the title.
Second check: another model agreed
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Typo Stray hyphens: "thermodynami-cally disfavored" and "*[Ru-(bpy)3]2+" in note [14], and "[Ru-(bpy)3]+ (3)" in the text on page 2; the complex is written [Ru(bpy)3] elsewhere.
- p. 5 Reference [14]
thermodynami-cally disfavored
- p. 5 Reference [14]
*[Ru-(bpy)3]2+
- p. 2 first paragraph
[Ru-(bpy)3]+ (3)
Judge's note: All three are printed mid-line on the page images (page 5 note [14]; page 2 first paragraph), so they are not line-break hyphens or extraction artefacts. The same paragraph on page 2 prints '[Ru(bpy)3]2+' without the hyphen.
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Typo Hünig's base is written two ways: "iPr2NEt" in the text and Table 1 entry 8, but "iPr2EtN" in Table 4 footnote [a] ("TBSOTf, iPr2EtN used instead of TESCl, LDA.") and in the Table 1 scheme.
- p. 10 Table 4 footnote [a]
iPr2EtN used instead of TESCl, LDA
- p. 2 Body text
iPr2NEt
- p. 10 Table 4 footnote a
iPr2EtN
Judge's note: Viewed the page 10 and page 7 images; the page 2 text has "iPr2NEt" twice. Both forms are printed. The Table 1 scheme also uses iPr2EtN while entry 8 of the same table uses iPr2NEt. Both are recognisable as the same compound, so this is a cosmetic inconsistency only.
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Typo Reference [3] reads "Organofluorine Chemistry, Principles and Comercial Applications"; "Comercial" should be "Commercial".
- p. 3 Reference [3]
Principles and Comercial
- p. 3
Organofluorine Chemistry, Principles and Comercial Applications. Springer;
- p. 3 Reference [3]
Principles and Comercial Applications
Judge's note: I checked the crop of the page 3 reference list. The page image prints "Comercial", so this is not an extraction artefact. "Comercial" is not an English word, so this is a misspelling regardless of the book's exact title.
Second check: another model agreed
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Typo Reference [2]: "Hiyama, T.; Yamamoto, H.; Hiyama, T.; Kanie, K.; Kusumoto, T.; Morizawa, Y.; Shimzu, M., editors." — 'Hiyama, T.' is listed twice, and 'Shimzu' is probably 'Shimizu'.
- p. 3 Reference [2]
Hiyama, T.; Yamamoto, H.; Hiyama, T.; Kanie, K.; Kusumoto, T.; Morizawa, Y.; Shimzu, M.
- p. 3 Reference [2]
Morizawa, Y.; Shimzu, M.
Judge's note: Read on the page 3 image; the name list is printed as quoted. The duplicated name is evident from the page itself. That 'Shimzu' should be 'Shimizu' rests on outside knowledge of the book's contributors (not verifiable from the files), though the printed form is very probably a dropped letter. The list also looks like a merge of author, editor and contributor names, which only the authors can sort out.
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Typo Reference [3]: "Banks, RE.; Smart, BE.; Tatlow, CJ., editors." — the editor's initials are probably transposed (J. C. Tatlow).
- p. 3 Reference [3]
Tatlow, CJ., editors
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: that the third editor of 'Organofluorine Chemistry: Principles and Commercial Applications' is J. C. Tatlow, so 'CJ.' should be 'JC.'. The page 3 image prints 'Tatlow, CJ.' as quoted; nothing in the files can confirm the correct initials.
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Typo Reference [7]: "an elegant catalytic α-trifluormethylation of enolsilanes" — 'trifluormethylation' should be 'trifluoromethylation'.
- p. 4 Reference [7]
catalytic α-trifluormethylation of enolsilanes
- p. 4
an elegant catalytic α-trifluormethylation of enolsilanes using
- p. 4 Ref. 7
α-trifluormethylation
- p. 3 Ref. 3
Comercial
Judge's note: Read on the page 4 image; the missing 'o' is printed as quoted, while the same sentence earlier has 'organometallic α-trifluoromethylation methods'. The 'Comercial' and 'Shimzu' items bundled into this cluster are recorded under C003 and C004.
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Typo Reference [9] l): "Neumann M, F ldner S, König B, Zeitler K." — a character is missing from the surname 'F ldner'.
- p. 4 Reference [9] l)
Neumann M, F ldner S, König B, Zeitler K.
Judge's note: The gap is visible on the page 4 image, so it is in the PDF and not only in the text layer; 'König' in the same entry is printed with its umlaut. That the intended name is 'Füldner' rests on outside knowledge, but a dropped accented glyph is evident from the page.
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Typo Reference [5] b): "Cleeren A, Ma Y, Seoc H-S, Leclercq G." — the author name 'Seoc' is probably 'Seo'.
- p. 4 Reference [5b]
Ma Y, Seoc H-S
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: that the ninth author of the cited Bioorg. Med. Chem. 2003, 11, 335 paper is H-S Seo. The page 4 image prints 'Seoc H-S' as quoted; the correct spelling cannot be verified from the files.
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Typo Reference [7] reads "an elegant catalytic α-trifluormethylation of enolsilanes using 2 mol%"; "trifluormethylation" should be "trifluoromethylation".
- p. 4
α-trifluormethylation of enolsilanes using 2 mol%
Judge's note: I checked the crop of reference [7] on page 4. The image prints "trifluormethylation". The same reference spells it "trifluoromethylation" a line earlier ("organometallic α-trifluoromethylation methods"), so this is a misspelling.
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Typo Reference [16] d): "Cantacuz ne D, Dorme R." — a character is missing from the surname 'Cantacuz ne'.
- p. 5 Reference [16] d)
Cantacuz ne D, Dorme R.
Judge's note: The gap is visible on the page 5 image, so it is in the PDF and not only in the text layer. That the intended name is 'Cantacuzène' rests on outside knowledge, but a dropped accented glyph is evident from the page.
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Typo Note [14] prints the peak potential as "EP = 1.03–1.26 V vs. SCE in MeCN" for silyl enol ethers and "Ep = 0.36–0.60 V vs. SCE in MeCN" for enamines: capital and lower-case subscript for the same quantity in one sentence.
- p. 5 Reference [14]
EP = 1.03–1.26 V vs. SCE in MeCN
- p. 5 Reference [14]
Ep = 0.36–0.60 V vs. SCE
- p. 5 Reference/note [14], silyl enol ethers
EP = 1.03–1.26 V
- p. 5 Reference/note [14], enamines
Ep = 0.36–0.60 V
Judge's note: On the page 5 image the first subscript is a capital P and the second a lower-case p. The sentence compares the two values directly as the same kind of potential, so they are not different quantities. Cosmetic; the meaning is unchanged.
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Typo Table 4 title prints "Direct, one-pot a-perfluoroalkylation of carbonyl compounds." with a Latin "a" in place of the Greek α.
- p. 10 Table 4 caption
Direct, one-pot a-perfluoroalkylation of carbonyl compounds.
Judge's note: Viewed the page 10 image. The title shows a plain Latin "a", while the labels in the same table ("α-CF3 ketone", "α-perfluoropropyl ester") and the keywords and text use α. It is in the page image, so not a text-layer artefact. It probably arose in conversion to the author-manuscript version, but it is in the PDF as provided.
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Typo Table 4 scheme gives the catalyst loading as "1. 0.5% 1, LDA, TESCl, 1 h;" where the text and Tables 1 and 3 write "0.5 mol%".
- p. 10 Table 4 scheme
0.5% 1, LDA, TESCl, 1 h
- p. 10 Table 4 scheme
0.5% 1, LDA, TESCl
Judge's note: Viewed the page 10 image: the scheme reads "0.5% 1". The Table 1 scheme (page 7) and Table 3 footnote [b] (page 9) print "0.5 mol%", as does the text. The meaning is unambiguous in context, so this is a minor unit-notation inconsistency in a scheme graphic.
Second check: none (judge only)