Organocalcium chemistry: preparation and reactions of highly reactive calcium

Wu, Tse Chong; Xiong, Huiming; Rieke, Reuben D.

doi:10.1021/jo00304a016

Cited by 94 publications

(35 citation statements)

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“…[8a] The preparation of active Ca, Sr, and Ba metals was performed as reported in the literature. [19] Synthesis of 2: A catalytic amount of MeSO 3 H (4 mL) was added slowly to a stirred solution of pyrrole (50 mL, 0.72 mol) and 5-nonanone (125 mL, 0.72 mol H 11.06, N 7.32; found C 81.87, H 11.13, N 7.35.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, we used the alkaline earth ions from calcium to barium. The metallation was carried out in THF by using the metal in an active form prepared as reported in the literature [19] (see Experimental Section). The final compounds, complexes 14 ± 18, contain two metal ions squeezed inside the same cavity that are p-bonded by the pyrrolyl anions and, in addition, bind two molecules of THF (Scheme 4).…”

Section: Introductionmentioning

confidence: 99%

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The π Complexation of Alkali and Alkaline Earth Ions by the Use ofmeso-Octaalkylporphyrinogen and Aromatic Hydrocarbons

et al. 2001

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The full metallation of meso-octaalkylporphyrinogens [R8N4H4] (R=Et, 1; nBu, 2; CH2Ph, 3; (CH2)4, 4) with heavy alkali metals (M = K, Rb, Cs) leads to the porphyrinogen-M4 compounds, in which the solvation of the alkali cations is largely assured by the intra- and intermolecular phi-interactions with the pyrrolyl anions. Such a mode of complexation results in a structural diversity as a function of the meso substituents, the size of the metal ion, and the solvent. The structure of the unsolvated polymers [R8N4M4]n (R= Et, M=K, 5; M=Rb, 6; M=Cs, 7; R= (CH2)4, M = Rb, 8; M = Cs, 9) have been clarified through the X-ray analysis of 7 recrystallized from diglyme. The structure shows that the tetraanion binds two Cs ions inside the cavity, which display in one case eta1:eta1:eta1:eta1 and in the other eta5:eta5:eta5:eta5 interaction modes. Bidimensional polymerization is assured by four Cs ions, which each bind at the eta5 position on the exo face of each pyrrole. With bulkier meso substituents, different polymeric forms are obtained (R = nBu, M = K, 10; M = Rb, 11; M = Cs, 12), and their structures were clarified through the X-ray analysis of 10, which was recrystallized from dimethoxyethane. The polymeric units are made up by the monomeric units [Bu8N4K2]2-, in which one potassium is eta1:eta1:eta1:eta5 and the other eta5:eta1:eta5:eta1 bonded inside the porphyrinogen cavity. In the case of R=CH2Ph, the monomeric anion [(PhCH2)8N4K2]2- (13) has been structurally identified. The metallation of 1 and 2 with active forms of alkaline earth metals (M' = Ca, Sr, Ba) led to dinuclear compounds [R,N4M'2] (R = Et, M' = Ca, 14; M'=Sr, 15; M'=Ba, 16; R=nBu. M'=Ba, 18), in which both metals inside the cavity are eta1:eta3:eta1:eta3 (Ca) and eta1:eta5:eta1:eta5 (Sr and Ba) bonded to the porphyrinogen tetraanion. The coordination sphere of each metal ion is completed by two THF molecules, which, in the case of Ba, are easily replaced by an arene ring [Bu8N4Ba2(eta6-arene)2] (arene=durene, 22; naphthalene, 23; toluene, 24; benzene, 25). The X-ray structures of 14, 15, 18, 22, and 23 are described in detail. We have tried to establish a relationship between the solid-state and solution structures by analyzing the 1H NMR spectra of the porphyrinogen complexes.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The π Complexation of Alkali and Alkaline Earth Ions by the Use ofmeso-Octaalkylporphyrinogen and Aromatic Hydrocarbons

et al. 2001

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“…'681 In view of the hitherto insignificance of the higher alkaline Table 6. Reactivity of organocalcium compounds [66] Halogen Yield Yield Halogen Yield Yield compound [%I [a] adamantane bromide [a] Upon reaction of the organocalcium compounds with cyclohexanone. [b] After transmetalation with CuCN .…”

Section: 7 * 29 3 7 621mentioning

confidence: 99%

Chemistry of and with Highly Reactive Metals

Fürstner

1993

Angew. Chem. Int. Ed. Engl.

222

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Today, the synthetic chemist has a large repertoire of metal activation methods at his disposal. After a first breakthrough was made at the beginning of the seventies with the introduction of the Rieke metals, a series of further, in part more efficient methods were describes, based on which not only classical metal-induced reactions could be substantially improved but also completely new reactions could be discovered. In this article the individual activation methods are discussed and compared as far as is possible using the currently available data. Especially noteworthy are the metal–graphite combinations because of their unsurpassed reactivity and concomitant easy preparation and manipulation. As shown by numerous applications of these reagents on polyfunctional substrates, particularly natural products, high reactivity of the metal and excellent selectivity are by no means precluded. Besides the purely preparative aspects also insights gained so far into the general principles and limits of metal activation are outlined, and attempts at determining the morphology of highly dispersed systems are reported

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“…[11] Accordingly, Rieke and co-workers utilized the corresponding calcium-diene compounds (via "highly reactive calcium" obtained from CaI 2 and preformed lithium biphenylide), which exhibited enhanced stereospecificity and regioselectivity in dialkylation reactions of α,ω-alkylene dihalides and dichlorosilanes. [12] In 1994, Mashima and Nakamura et al presented the first Xray structure determination of 1,3-diene complexes of the heavier alkaline earth metals calcium and strontium, [M(2,3-dimethyl-1,4-diphenyl-1,3-butadiene)(thf) 4 ] (M = Ca, Sr). [13] Whereas the presence of two methyl groups further enhanced the solubility, simultaneously counteracting the formation of oligomeric species, the solid-state structures revealed a η 4 coordination of the s-cis-oriented diene ligand.…”

Section: Introductionmentioning

confidence: 99%

Diene Dissolution of the Heavier Alkaline Earth Metals

et al. 2012

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Alkaline and alkaline earth metals are efficiently activated in the presence of aromatic hydrocarbons ("potassium-naphthalene", "magnesium-anthracene") or (substituted) 1,3-dienes to produce well-defined organometallic complexes. In this study, mononuclear diene complexes of calcium, strontium, and barium have been synthesized by utilizing tailormade 1,3-dienes. Complexes [M(2,3-dimethyl-1,4-ditolyl-1,3-butadiene)(thf) 4 ] (M = Ca, Sr), [Ca(2,3-dimethyl-1,4-dinaphthyl-1,3-butadiene)(thf) 4 ], and {Ba [2,3-dimethyl-1,4-

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Organocalcium chemistry: preparation and reactions of highly reactive calcium

Cited by 94 publications

References 0 publications

The π Complexation of Alkali and Alkaline Earth Ions by the Use ofmeso-Octaalkylporphyrinogen and Aromatic Hydrocarbons

The π Complexation of Alkali and Alkaline Earth Ions by the Use ofmeso-Octaalkylporphyrinogen and Aromatic Hydrocarbons

Chemistry of and with Highly Reactive Metals

Diene Dissolution of the Heavier Alkaline Earth Metals

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