Iron-catalysed Suzuki coupling? A cautionary tale

Bedford, Robin B.; Nakamura, Masaharu; Gower, Nicholas J.; Haddow, Mairi F.; Hall, Mark A.; Huwe, Michael; Hashimoto, Toru; Okopie, Rukeme A.

doi:10.1016/j.tetlet.2009.08.022

Cited by 73 publications

(25 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Importantly, a repeat of the reaction outlined in entry 10 gave no product when the CoCl 2 was omitted, whereas repeating the reaction in entry 14 with high purity CoCl 2 (99.999%) gave 2 a in essentially quantitative yield. This finding indicates that impurities, in either the cobalt source or one of the other components of the reaction mixture, are not responsible for the observed catalytic activity …”

Section: Methodsmentioning

confidence: 93%

“…Of the EAM alternatives to palladium for Suzuki biaryl coupling, first‐row transition metals are particularly attractive, with nickel‐based catalysts being the most well developed to date . Iron‐catalyzed Suzuki cross‐coupling can be performed between a variety of organic halides and organoboron reagents, but simple biaryl bond formation remains elusive and challenging . Recently, Chirik and co‐workers reported early results in the coupling of aryl triflates with arylboron pinacol esters by using a cobalt PNP‐pincer‐based catalyst .…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Cobalt‐Catalyzed Suzuki Biaryl Coupling of Aryl Halides

et al. 2017

Self Cite

View full text Add to dashboard Cite

Readily accessed cobalt pre-catalysts with N-heterocyclic carbene ligands catalyze the Suzuki cross-coupling of aryl chlorides and bromides with alkyllithium-activated arylboronic pinacolate esters.P reliminary mechanistic studies indicate that the cobalt species is reduced to Co 0 during the reaction.The palladium-catalyzed cross-coupling of organoboronic acids or esters with organic halides or related substrates-the Suzuki reaction-is ap owerful and very widely exploited method for the formation of biaryl compounds (Scheme 1). [1] This reaction is used commercially for the production of arange of materials,including the sartan class of angiotensin inhibitors for the treatment of hypertension (e.g. Lorsartan) and Boscalid, abroad-spectrum agrochemical fungicide.[2]While palladium-based catalysts are ubiquitous in Suzuki cross-coupling reactions,there is agrowing impetus to replace them with more sustainable alternatives based on earthabundant metals (EAM). This is not only because of the fact that palladium, like all platinum-group metals (PGMs), is scarce and expensive,b ut also because of the relatively high toxicity of PGMs;asac onsequence of this toxicity there are strict regulations in place for the removal of PGMs to the low ppm level from active pharmaceutical intermediates.[3] Of the EAM alternatives to palladium for Suzuki biaryl coupling, first-row transition metals are particularly attractive,w ith nickel-based catalysts being the most well developed to date. [4,5] Iron-catalyzed Suzuki cross-coupling can be performed between avariety of organic halides and organoboron reagents, [6] but simple biaryl bond formation remains elusive and challenging. [6a, 7, 8] Recently,C hirik and co-workers reported early results in the coupling of aryl triflates with arylboron pinacol esters by using ac obalt PNP-pincer-based catalyst.[9] We now report the cross-coupling of aryl chlorides and bromides with activated arylboronic pinacol esters, [10,11] using simple cobalt catalysts prepared in situ from commercially available precursors.Ther esults shown in Table 1s ummarize selected [12] optimization studies using 4-chorotoluene and the activated phenylboronic ester 1a, [6b,c,e, 8] catalyzed by species formed in situ from cobalt(II) chloride with ar ange of different ligands and ligand precursors.No reaction was observed in the absence of added ligand (Table 1, entry 1) and little or no product 2a was obtained when mono,b i-, or tridentate phosphine ligands were tested Scheme 1. Palladium-catalyzed Suzuki biaryl coupling and selected products.

show abstract

Section: Methodsmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Cobalt‐Catalyzed Suzuki Biaryl Coupling of Aryl Halides

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…It has been shown that ppb quantities of Pd impurities can catalyze cross-coupling chemistry [100][101][102]. For example, a palladium-free, ironcatalyzed Suzuki reaction presented by Franzén [103] was later shown to be not reproducible [104], and the original paper has subsequently been retracted.…”

Section: Enantioselective Iron Catalysis and Stoichiometric Consideramentioning

confidence: 99%

Iron Catalysis: Historic Overview and Current Trends

Bauer

2015

Topics in Organometallic Chemistry

View full text Add to dashboard Cite

Iron catalysis is a growing area of research, as seen by an exponential increase in the publication activities on the topic. This introductory chapter provides a historic overview of the development of iron catalysis including some notable milestones. The advantages of iron, i.e., its abundance, low price, and relative nontoxicity, are discussed, and an overview of the main type of reactions catalyzed by iron is outlined. The advances of heterogeneous iron catalysis (which is not covered in this volume) are exemplified with a few notable cases. Finally, the potential impact of metal impurities in iron sources on the catalytic activity is discussed.

show abstract

“…Although three iron-catalyzed biaryl cross-coupling reactions have been reported, two have been retracted. [5] Bedfords research group and our group have reported iron-catalyzed Suzuki-Miyaura coupling reactions of aryl-or alkenylboron reagents with the aid of iron-bisphosphine catalysts. [6] Herein we report the first ironcatalyzed alkyl-alkyl Suzuki-Miyaura coupling reaction wherein alkylboron compounds and non-activated alkyl halides are cross-coupled in high yields with a catalyst combination of an iron salt and a bisphosphine with a large bite angle, Xantphos (9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene), thereby providing a new method for the most challenging combination of cross-coupling partners.…”

mentioning

confidence: 99%