Top Ten Papers

Personal Reference, Most Recent First

1.   Photoredox catalysis with aryl sulfonium salts enables site-selective late-stage fluorination

Arylthianthrenium salts can be conceptually superior electrophiles compared to other (pseudo)halides in photoredox/ copper-catalyzed cross coupling reactions. A physical organic analysis rationalizes the first selective, two-step aromatic C–H to C–F synthesis of aryl fluorides via arylsulfonium salts.

J. Li, J. Chen, R. Sang, W.S. Ham, M.B. Plutschack, F. Berger, S. Chabbra, A. Schnegg, C. Genicot, T. Ritter “Photoredox catalysis with aryl sulfonium salts enables site-selective late-stage fluorination“ Nature Chem. 2019,
DOI: 10.1038/s41557-019-0353-3.

2.  Site-selective and versatile aromatic C−H functionalization by thianthrenation

Exquisitely selective aromatic C–H functionalization was achieved by a new transformation to make arylthianthrenium salts. The sulfonium salts were shown to participate in 14 different cross coupling reactions often outperforming conventional leaving groups such as bromide and iodide in both transition-metal- and photoredox-catalyzed reactions.

F. Berger, M. B. Plutschack, J. Riegger, W. Yu, S. Speicher, M. Ho, N. Frank, T. Ritter “Site-selective and versatile aromatic C−H functionalization by thianthrenation“ Nature 2019, 567, 223–228

DOI: 10.1038/s41586-019-0982-0

3.  Late-Stage Aromatic C–H Oxygenation

The electrophilic bismesylperoxide enabled an unusually functional group-tolerant oxygenation of complex small arenes. An identified arene-peroxide charge transfer complex may be responsible for the chemoselectivity for arene functionalization in the presence of a wide variety of other functional groups, which is challenging with other reagents.

J. Börgel, L. Tanwar, F. Berger, T. Ritter “Late-Stage Aromatic C–H Oxygenation“ J. Am. Chem. Soc. 2018, 140, 16026–16031.

DOI: 10.1021/jacs.8b09208

4.  Catalytic dehydrogenative decarboxyolefination of carboxylic acids

A combination of cobalt and iridium catalysts enabled the synthesis of alpha olefins from carboxylic acids, including fatty acids. The transformation is the first of its kind that does not require the addition of any additive in stoichiometric amount, which is a prerequisite for sustainable synthesis on scale in this field.

X. Sun, J. Chen, T. Ritter “Catalytic dehydrogenative decarboxyolefination of carboxylic acids“ Nat. Chem. 2018, 10, 1229–1233.

DOI: 10.1038/s41557-018-0142-4

5.  Palladium-catalysed electrophilic aromatic C–H fluorination

The first catalyzed direct fluorination reaction of arenes. Catalyst design resulted in a high-valent transition-metal fluoride, capable of electrophilic fluorination through an unusual Pd(III) transition state.

K. Yamamoto, J. Li, J. A. O. Garber, J. D. Rolfes, G. B. Boursalian, J. C. Borghs, C. Genicot, J. Jacq, M. van Gastel, F. Neese, T. Ritter “Palladium-catalysed electrophilic aromatic C–H fluorination” Nature 2018, 554, 511–514.

DOI: 10.1038/nature25749

6.  Concerted nucleophilic aromatic substitution (CSNAr) with 19F and 18F

The synthesis of F-18-labeled molecules from phenols by deoxyfluorination was developed and investigated in mechanistic detail. The nucleophilic aromatic substitution also proceeds on electron-rich arenes such as anilines, which is possible through a concerted transition state as opposed to generally accepted Meisenheimer complexes. Subsequent to our work, concerted nucleophilic aromatic substitution has become more accepted as a viable and possibly even common pathway in SNAr reactions.

C. N. Neumann, J. M. Hooker, T. Ritter “Concerted nucleophilic aromatic substitution (CSNAr) with 19F and 18FNature 2016, 534, 369–373.

DOI: 10.1038/nature17667

7.  A fluoride-derived electrophilic late-stage fluorination reagent for PET imaging

A specially designed palladium complex can adsorb fluoride to generate an electrophilic fluorinating reagent. Conceptually, the manuscript addressed the challenge of performing electrophilic fluorination with 18F fluoride as ultimate source of fluorine, and is one of the first accounts on employing transition metal reactivity for the synthesis of potential PET ligands.

E. Lee, A. S. Kamlet, D. C. Powers, C. N. Neumann, G. B. Boursalian, T. Furuya, D. C. Choi, J. M. Hooker, T. Ritter “A fluoride-derived electrophilic late-stage fluorination reagent for PET imaging” Science 2011, 334, 639–642.

DOI: 10.1126/science.1212625

8.  Deoxyfluorination of phenols

The first aromatic deoxyfluorination reaction, and the development of the now commercially available reagent PhenoFluor.

P. Tang, W. Wang, T. Ritter “Deoxyfluorination of phenols” J. Am. Chem. Soc. 2011, 133, 11482‑11484.

DOI: 10.1021/ja2048072

9.  Bimetallic Pd(III) Complexes in Palladium-Catalyzed Carbon–Heteroatom Bond Formation

The first recognized organometallic reactivity of Pd(III) was described, and the relevance of Pd(III) to oxidative palladium catalysis was demonstrated for the first time. With over 400 citations, this manuscript remains one of the most highly cited original contributions to Nature Chemistry.

D. P. Powers, T. Ritter “Bimetallic Pd(III) Complexes in Palladium-Catalyzed Carbon–Heteroatom Bond Formation” Nature Chem. 2009, 1, 302–309.

DOI: 10.1038/nchem.246

10. Carbon–Fluorine Reductive Elimination from a High-Valent Palladium Fluoride

Design of the pyridylsulfonamide ligand enabled the first observed reductive elimination of a C–F bond. The manuscript laid the basis for the understanding and development of transition-metal-mediated and –catalyzed carbon-fluorine bond formation.

T. Furuya, T. Ritter “Carbon–Fluorine Reductive Elimination from a High-Valent Palladium Fluoride” J. Am. Chem. Soc. 2008, 130, 10060–10061.

DOI: 10.1021/ja803187x


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