Organometallic reaction mechanisms. 14. Role of transition metal catalysts in the formation of aromatic pinacols and hydrols during Grignard reagent addition to ketones

Ashby, E. C.; Buhler, Jerry D.; Lopp, Irene G.; WIESEMANN, T. L.; Bowers, Joseph S.; Laemmle, J.

doi:10.1021/ja00437a025

Cited by 31 publications

(15 citation statements)

References 5 publications

(5 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This result is highly reminiscent of early work of Ashby et al who found that the amount of pinacol produced in attempted additions of MeMgBr to aromatic ketones is directly proportional to the iron impurities of the magnesium metal used to form the Grignard reagent. [22] Our results, therefore, suggest that the reagent responsible for this striking correlation is an ate-complex of the type described herein. [23] More generally speaking, this finding sheds light into the well established but hardly understood "alchemistic" effects exerted by certain transition-metal residues on the course of Grignard reactions.…”

supporting

confidence: 59%

Unusual Structure and Reactivity of a Homoleptic “Super‐Ate” Complex of Iron: Implications for Grignard Additions, Cross‐Coupling Reactions, and the Kharasch Deconjugation

Fürstner¹,

Krause²,

Lehmann³

2006

Angew Chem Int Ed

147

View full text Add to dashboard Cite

Our recent investigations on iron-catalyzed cross-coupling reactions of organomagnesium reagents with various electrophiles were guided by the perception that bare, low-valent iron clusters formed in situ according to Scheme 1 might account for the observed turnover. [1][2][3][4][5] Since the analysis of the released gas suggests that this reduction process involves a b-hydride elimination/reductive coupling event, [6] it should proceed only with Grignard reagents containing at least two Scheme 1. Proposed formation of low-valent, intermetallic iron clusters serving as the actual catalysts in cross-coupling reactions of aryl chlorides and alkyl Grignard reagents with two or more carbon atoms. NMP = N-methylpyrrolidone.

show abstract

supporting

confidence: 59%

Unusual Structure and Reactivity of a Homoleptic “Super‐Ate” Complex of Iron: Implications for Grignard Additions, Cross‐Coupling Reactions, and the Kharasch Deconjugation

Fürstner¹,

Krause²,

Lehmann³

2006

Angew Chem Int Ed

147

View full text Add to dashboard Cite

show abstract

“…In addition, the iron acts as a catalyst to increase the rate after a site is initiated. Of course, iron is known to increase side reactions and should be used with caution. , …”

Section: Resultsmentioning

confidence: 99%

Reactivity of Magnesium Surfaces during the Formation of Grignard Reagents

Teerlinck

Bowyer

1996

J. Org. Chem.

View full text Add to dashboard Cite

A reaction cell which allows for photomicrographic observation of magnesium surfaces during formation of Grignard reagents is described. As the reaction proceeds, a finite number of discrete sites initiate relatively rapidly. Following this stage, the reactive area increases by the growth of sites rather than by the initiation of new sites. Sites are randomly located across the magnesium surface (neither clustered nor dispersed) consistent with their formation at crystalline defects or metallic impurities. Various methods of magnesium surface activation are tested. For example, iodine and ferric chloride increase reactivity by increasing the density of reactive sites and by increasing the rate at which individual sites react. Scratching the magnesium surface increases reactivity by decreasing the time required for initiation of reactive sites. A mercury/magnesium amalgam provides a uniformly reactive surface, but the reaction rate is very slow.

show abstract

“…In this way the value of ¿2 can be calculated being 3.6 X 10-4 s_1 for la and 22.7 X 10-4 s_1 for lb. The validity of the chosen model can be tested by substituting the calculated values for k\ and /c2 in eq 3 (calculation of [10]) and eq 4 (calculation of [11] + [4]): can be rejected as an intermediate on basis of the results obtained by Prinzbach and coworkers44 for the analogous AgBF4 catalyzed reaction of unsubstituted 3-oxaquadricyclane. To obtain more insight in the reaction of 1 with AgC104 (in benzene solution) the and 13C NMR spectral changes were monitored during the course of the reactions.…”

Section: B Reaction Mechanisms 1 Thermal and Acid Catalyzedmentioning

confidence: 99%

“…Journal of the American Chemical Society 1 1OO:lO / M a y 10,1978 1-(2,4-DirnethylphenyI)-l-phenylethanol. To a solution of 0.325 g (1.15 mmol) of 2,4-dimethylbenzophenone in 10 mL of ether was added 2.86 mmol of CH3MgBr in 2.6 mL of ether.…”

mentioning

confidence: 99%

Mechanistic aspects of transition metal and trichloroacetic acid catalyzed reactions of 3-oxaquadricyclanes

Hogeveen¹,

Nusse²

1978

J. Am. Chem. Soc.

View full text Add to dashboard Cite

The reactivity of 1,5-dicarbomethoxy-3-oxaquadricyclanes toward different catalysts has been found to vary strongly with the type of catalyst used. The various reactions initiate at different sites in the substrates: CC13COOH reacts at a cyclopropyl ring atom with inversion of configuration; Rh2(CO)dC12 reacts preferentially as a Lewis acid at the C-0-C fragment; to a minor extent oxidative addition of a cyclopropyl ring to the rhodium(1) complex occurs as in the case of the Pd(C6HsCN)2-Cl2 catalyzed reaction; a kinetic analysis shows that the AgC104 catalyzed reaction initiates at two sites (at the C-0-C fragment and at a cyclopropyl ring), both leading to the same reaction product. Compound l b reacts much faster than l a in the thermal and CC13COOH catalyzed reactions in contrast to the metal catalyzed processes.

show abstract

Organometallic reaction mechanisms. 14. Role of transition metal catalysts in the formation of aromatic pinacols and hydrols during Grignard reagent addition to ketones

Cited by 31 publications

References 5 publications

Unusual Structure and Reactivity of a Homoleptic “Super‐Ate” Complex of Iron: Implications for Grignard Additions, Cross‐Coupling Reactions, and the Kharasch Deconjugation

Unusual Structure and Reactivity of a Homoleptic “Super‐Ate” Complex of Iron: Implications for Grignard Additions, Cross‐Coupling Reactions, and the Kharasch Deconjugation

Reactivity of Magnesium Surfaces during the Formation of Grignard Reagents

Mechanistic aspects of transition metal and trichloroacetic acid catalyzed reactions of 3-oxaquadricyclanes

Contact Info

Product

Resources

About