Reactions of alkenylchromium reagents prepared from alkenyl trifluoromethanesulfonates (triflates) with chromium(II) chloride under nickel catalysis

Takai, Kazuhiko; Tagashira, Mizuka; Kuroda, Tooru; Oshima, Koichiro; Utimoto, Kiitirô; Nozaki, Hitosi

doi:10.1021/ja00279a068

Cited by 457 publications

(188 citation statements)

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“…Considering that metal contaminants have also been found relevant in other processes involving metals (such as the chromium-mediated Nozaki-Hiyama-Kishi reaction, [10] olefinations and Simmons-Smith reactions with organozinc reagents, [11] and "metal-free" Suzuki- [12] and Sonogashira-coupling [13] ), we suspect that the presence of trace metal impurities may play a more important role than is generally assumed. …”

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confidence: 99%

On the Role of Metal Contaminants in Catalyses with FeCl₃

2009

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Metal catalysis has a dominant role in modern organic chemistry. In particular, crosscoupling reactions allow bond formations, which have previously been impossible to perform. [1] Precious metal catalysts dominate the field, but alternative systems based on nickel and copper salts have also, historically, been important. In particular, recent systems based on these metals have been described that provide products in a highly efficient manner. [2] In this context, one of us (C.B.) reported iron-catalyzed cross-couplings leading to arylated amides, phenols, thiols and alkynes. [3,4] Commonly, 10 mol % of an iron salt in combination with 20 mol % of a ligand (a diamine or a diketone) in a solvent such as toluene at 135 °C (using closed vials) was used. It was noticed by chemists at RWTH and MIT (past and present) that the catalyst activity depended on the metal salt purity and even more so on its commercial source. [5] Also, a parallel between the results with the iron systems and some of those realized with copper catalysts by S.L.B.'s group and that of Song was recognized. For example, as in the case of much of the chemistry from S.L.B.'s group, N,N'-dimethyl-1,2-diamines were superior ligands, and the best results were realized in conversions of aryl iodides.These observations prompted us to collaborate to investigate whether it was possible that trace amounts of copper impurities were influencing these reactions. Thus, different sources of FeCl 3 (from >98-99.99% metal purity) were examined in the couplings of pyrazole, phenyl amide, phenol and thiophenol with aryl iodides. The literature data and the new results (obtained by B. Fors and R. Martin in the S.L.B. group) are shown below (Tables 1-4).In all cases when >99.99% FeCl 3 was employed lower yields were obtained than when the reactions were run using >98% FeCl 3 . [6,7] Furthermore, when different sources of >98% FeCl 3 were used different results were observed. These findings suggest that both the purity and the source of the FeCl 3 play a crucial role in the success of these transformations.In order to further investigate the cause of these findings, small amounts of Cu 2 O were added to the reactions using >99.99% FeCl 3 . With only 10 ppm of Cu 2 O a significant increase in yield was observed in all cases. [8,9] Moreover, in two cases examined, essentially (Tables 1 and 2, last entries).Although questions remain, we conclude that the outcome of the reported reactions with FeCl 3 may in certain cases be significantly affected by trace quantities of other metals, particularly copper. Considering that metal contaminants have also been found relevant in other processes involving metals (such as the chromium-mediated Nozaki-Hiyama-Kishi reaction, [10] olefinations and Simmons-Smith reactions with organozinc reagents, [11] and "metal-free" Suzuki- [12] and Sonogashira-coupling [13] ), we suspect that the presence of trace metal impurities may play a more important role than is generally assumed.

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On the Role of Metal Contaminants in Catalyses with FeCl₃

2009

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“…In this case, the allyl group should be manipulated by removing one carbon atom. After construction of the acyclic enediyne, we planned to accomplish the ring formation through the Nozaki reaction, 19 which is probably the most general and efficient reaction employed in enediyne synthesis for the crucial closure of the mesocyclic ring. Before starting the synthesis we had to select the R 1 and R 3 groups.…”

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Synthetic approaches towards a new class of strained "lactenediynes"

Banfi¹,

Basso²,

Guanti³

et al. 2006

Arkivoc

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The paper described two alternative synthetic approaches towards a new class of strained "lactenediynes", compounds where a 10-membered enediyne ring is fused with a β-lactam. Although the two alternative syntheses were successful up to the last step, the cyclization to give the desired products failed in both cases, probably because of excessive steric strain in the products. In one of the two approaches (which was the most efficient one in terms of overall yield) a mixture of diastereoisomeric cyclodimers was isolated in moderate yield. A certain degree of stereoselectivity was observed. These compounds may be interesting as new supramolecular systems.

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“…By addition of a catalytic amount of NiCl 2 to CrCl 2 , the desired Barbier-type addition of haloalkenes to aldehydes occurs with good reproducibility (Scheme 11). 17,18 It was important to keep the content of nickel(II) chloride low (about 0.011%w/w) to avoid the formation of dienes derived by homocoupling of the haloalkenes. Other potential catalysts, such as manganese(II) chloride, iron(III) chloride, cobalt(II) chloride, copper(I) chloride, and palladium(II) chloride, were not as effective.…”

Section: 15mentioning

confidence: 99%

“…Therefore, we analyzed the effective and ineffective lots by fluorescent X-ray, and found that in the lot containing nickel as the major contaminant, the amount of nickel was about 0.5 mol % based on chromium (Figure 1). 17 During 19821985, Nozaki was the lead investigator of the Grant-in-Aid for Scientific Research on Priority Areas "Innovative Studies on Highly Selective Synthesis" of MEXT Japan. In 1985, Kishi at Harvard University presented his research toward the total synthesis of palytoxin as an invited lecturer at the symposium for the grant in Kyoto.…”

Section: 15mentioning

confidence: 99%

Trace Amounts of Second Metal Elements Can Play a Key Role in the Generation of Organometallic Compounds

Takai

2015

Bulletin of the Chemical Society of Japan

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). He has developed several synthetic methods using early transition metals such as chromium, titanium, and tantalum. Current research in his group is aimed towards the use of the complexes of group 7 metals as catalysts in organic synthesis and C-H activation initiated by insertion of transition metals into heteroatom-hydrogen bonds. AbstractDuring the development of new synthetic organic reactions by the use of group 47 metals, we twice encountered a reproducibility problem. The key factor was trace amounts of second metal elements that contaminated the first, main metals, i.e., nickel in chromium and lead in zinc. We had determined the standard procedures for these reactions and they were adopted in Organic Syntheses. The difference in the source of zinc, i.e., contamination by a catalytic amount of lead, proved to affect both the reactivity of the SimmonsSmith reaction and the formation of alkylzinc from the corresponding iodides. By using the concept of catalytic effects of the second metals, we developed a method to use manganese metal and applied this to sequential radical and anionic reactions. In addition, allylic aluminum species were prepared smoothly from allylic halides and aluminum by addition of an indium salt, the second element. In this account, I describe how the synthetic methods were discovered and developed, with an emphasis on the stories behind the communications and articles.

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Reactions of alkenylchromium reagents prepared from alkenyl trifluoromethanesulfonates (triflates) with chromium(II) chloride under nickel catalysis

Cited by 457 publications

References 2 publications

On the Role of Metal Contaminants in Catalyses with FeCl₃

On the Role of Metal Contaminants in Catalyses with FeCl₃

Synthetic approaches towards a new class of strained "lactenediynes"

Trace Amounts of Second Metal Elements Can Play a Key Role in the Generation of Organometallic Compounds

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Reactions of alkenylchromium reagents prepared from alkenyl trifluoromethanesulfonates (triflates) with chromium(II) chloride under nickel catalysis

Cited by 457 publications

References 2 publications

On the Role of Metal Contaminants in Catalyses with FeCl3

On the Role of Metal Contaminants in Catalyses with FeCl3

Synthetic approaches towards a new class of strained "lactenediynes"

Trace Amounts of Second Metal Elements Can Play a Key Role in the Generation of Organometallic Compounds

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On the Role of Metal Contaminants in Catalyses with FeCl₃

On the Role of Metal Contaminants in Catalyses with FeCl₃