Synthesis of metal carbonyl monoanions by trialkylborohydride cleavage of metal carbonyl dimers: a convenient one-flask preparation of metal alkyls, metal acyls, and mixed-metal compounds

Gladysz, J. A.; Williams, Geoffrey M.; Tam, William; Johnson, Dennis L.; Parker, David W.; Selover, J. C.

doi:10.1021/ic50193a006

Cited by 134 publications

(44 citation statements)

References 10 publications

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“…Li(C 2 H 5 ) 3 BH was purchased from Aldrich. [Mn 2 (CO) 8 (PPh 3 ) 2 ] , [28] Li[Mn(CO) 5 ], [29] [(h 5 -C 5 H 5 )Ru(dppm)Cl], [30] [(h 5 -C 5 H 5 )Ru(dppm)H], [31] [h 5 -C 5 (CH 3 ) 5 ]Ru-(dppm)Cl], [8] [h 5 -C 5 (CH 3 ) 5 ]Ru(dppm)H], [8] [(h 5 -C 5 H 5 )Ru(CO)-(dppm)]I, [32] and [(h 5 -C 5 H 5 )Ru(CO)(PPh 3 )(CH 3 CN)]BF 4 [33] were prepared according to published procedures. [HMn(CO) 5 ] was synthesized according to a literature procedure except that Li(C 2 H 5 ) 3 BH was used instead of Na/Hg.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Heterobimetallic RuMn Complexes and the Coupling Reactions of Epoxides with Carbon Dioxide Catalyzed by these Complexes

Man

Lam

Sit

et al. 2006

Chemistry A European J

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The heterobimetallic complexes [(eta5-C5H5)Ru(CO)(mu-dppm)Mn(CO)4] and [(eta5-C5Me5)Ru(mu-dppm)(mu-CO)2Mn(CO)3] (dppm = bis-diphenylphosphinomethane) have been prepared by reacting the hydridic complexes [(eta5-C5H5)Ru(dppm)H] and [(eta5-C5Me5)Ru(dppm)H], respectively, with the protonic [HMn(CO)5] complex. The bimetallic complexes can also be synthesized through metathetical reactions between [(eta5-C5R5)Ru(dppm)Cl] (R = H or Me) and Li+[Mn(CO)5]-. Although the complexes fail to catalyze the hydrogenation of CO2 to formic acid, they catalyze the coupling reactions of epoxides with carbon dioxide to yield cyclic carbonates. Two possible reaction pathways for the coupling reactions have been proposed. Both routes begin with heterolytic cleavage of the RuMn bond and coordination of an epoxide molecule to the Lewis acidic ruthenium center. In Route I, the Lewis basic manganese center activates the CO2 by forming the metallocarboxylate anion which then ring-opens the epoxide; subsequent ring-closure gives the cyclic carbonate. In Route II, the nucleophilic manganese center ring-opens the ruthenium-attached epoxide to afford an alkoxide intermediate; CO2 insertion into the RuO bond followed by ring-closure yields the product. Density functional calculations at the B3LYP level of theory were carried out to understand the structural and energetic aspects of the two possible reaction pathways. The results of the calculations indicate that Route II is favored over Route I.

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Section: Methodsmentioning

confidence: 99%

Synthesis of Heterobimetallic RuMn Complexes and the Coupling Reactions of Epoxides with Carbon Dioxide Catalyzed by these Complexes

Man

Lam

Sit

et al. 2006

Chemistry A European J

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“…No separation is required since the hydrogen byproduct is evolved upon formation (Scheme 3). Gladysz et al [45] used the trialkylborohydride K-Selectride ® [(sec-C 4 H 9 ) 3 BH − ] K + to achieve the same goal, although in this procedure the trialkylborane must be removed (Scheme 3) [39]. Rück-Braun has used the Gladysz procedure to efficiently prepare an Fp cationic carbene complex from Fp anion in one pot [46].…”

Section: Synthesis Of the ( 5 -C 5 H 5 )(Co) 2 Fe Metalatementioning

confidence: 99%

Recent chemistry of the η5-cyclopentadienyl dicarbonyl iron anion

Theys

Dudley

Hossain

2009

Coordination Chemistry Reviews

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“…Gladysz has shown that metal carbonyl anions can be generated by the addition of a borohydride source to the metal carbonyl dimer, [CpMo(CO) 3 ] 2 . 13 We used this technique to generate the molybdenum anion, and applied it to the isolobal displacement reaction. To the best of our knowledge, this is the first time these complexes have been generated in this manner and this procedure represents a much simpler and more effective method of synthesis of heterobimetallic alkyne complexes of this type.…”

Section: Methodsmentioning

confidence: 99%

“…The reaction mixture was then allowed to warm to r.t. The reaction mixture was filtered through a pad of celite and silica to remove any metal residues and then concentrated in vacuo to give the product 2c as red crystals (0.537 g, 95% 13 …”

Section: Preparation Of 2cmentioning

confidence: 99%

Formation of Propargylic Stereocentres using Desymmetrised Alkyne Complexes

Fletcher¹,

Fryatt²,

Rutherford³

et al. 2001

Synlett

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Addition of Grignard reagents to alkynyl aldehyde complexed bimetallic system proceeds with good to excellent stereocontrol.The creation of chiral centres at propargylic (prop-1-ynyl) positions has received some interest in the past few years. Methods for the preparation of stereocentres next to alkynes include the addition of nucleophiles to propargylic aldehydes using titanium catalysis 1 and boron reagents 2 and a metal catalysed ene reaction. 3 The other main methods have been the hydride reduction of propargylic ketones with chiral borohydrides, 4 in particular the CBS oxazaborolidine catalyst system 5 and by transfer hydrogenation. 6 The importance of this chemistry is perhaps best illustrated when the newly formed stereocentre is used in the preparation of complex natural products, such as macrolactin, 2 isocarbacylin derivatives, 3 methyl nonactate 4a and scopadulcic acid. 4cOur interest in metal alkyne chemistry prompted us to find a new method for the generation of propargylic stereocentres. Of relevance to this are the extensive studies by Nicholas 7 and Hanaoka 8 on the addition of enols and enolates to complexed propargylic aldehydes. The metal group facilitates high diastereocontrol in the reaction, and can be readily removed to leave the organic fragment with the newly created chiral centres. In addition, Nicholas has shown that phosphine substituted cobalt alkyne complexes can be used to form enantio-enriched propargylic stereocentres since the complex itself is rendered chiral by the introduction of the phosphine ligand. 9 Access to products of this type has been achieved, again by Nicholas, by adding the PPh 3 ligand to the propargylic alcohol complexes. 10 However, the diastereoselectivity was highly dependant on the size of the substituents. Remarkably, there have been, to the best of our knowledge, no reports of addition of Grignard or organolithium reagents to the same types of complexes.Starting with 2-butyn-1-al diethyl acetal (Scheme 1), complexation to cobalt was achieved simply by stirring with Co 2 (CO) 8 in DCM. Treatment of the acetal with a catalytic amount of p-toluene sulfonic acid gave the aldehyde. This was then reacted with triphenyl phosphine to produce the desired complex 1a. Complex 1b was prepared in an analogous manner from propynal. Scheme 1With the desired aldehyde in hand, we reacted this with a series of nucleophiles. All the reactions outlined in Scheme 2 proceeded quickly at low temperature (-78°C) in THF to give the corresponding alcohols. The diastereoisomeric excess was measured directly in most cases since the complexes were easily separable by chromatography. With inseparable complexes, the diasteromeric excess was estimated from the 1 H NMR spectra. The results show that excellent diastereoisomeric excesses are achieved with all the nucleophiles we studied. Scheme 2In order to account for the stereocontrol, we obtained Xray crystal structures of the starting metal alkyne complex and one of the products. 11 The aldehyde, 1a, is shown in Figure 1. The complex a...

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Synthesis of metal carbonyl monoanions by trialkylborohydride cleavage of metal carbonyl dimers: a convenient one-flask preparation of metal alkyls, metal acyls, and mixed-metal compounds

Cited by 134 publications

References 10 publications

Synthesis of Heterobimetallic RuMn Complexes and the Coupling Reactions of Epoxides with Carbon Dioxide Catalyzed by these Complexes

Synthesis of Heterobimetallic RuMn Complexes and the Coupling Reactions of Epoxides with Carbon Dioxide Catalyzed by these Complexes

Recent chemistry of the η5-cyclopentadienyl dicarbonyl iron anion

Formation of Propargylic Stereocentres using Desymmetrised Alkyne Complexes

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