Malonate ion

Irradiation accelerates the reactions of Scheme 4.1, and the substitution products are formed in 70-80% yields. Acceptors of radicals (e.g., di-tert-butylnitroxyl) or electrons (e.g., m-dinitro-benzene [DNB]) completely inhibit the snbstitution even if the acceptors are added to the reaction mixture in small amonnts. The mentioned snbstitution reactions do not take place when no cyano groups are present in the initial a-phenylsnlphonyl cumene. Hence, the cyano groups send the reaction via the ion-radical pathway. Like the nitro gronp, the cyano group promotes the formation of anion-radical, which originates on one-electron transfer from the thiophenolate or malonate ions to the substrate. 

The versatility of host 5 and related forms has recently been highlighted by Martell et al. who have shown 5-4H to effectively complex malonate in aqueous solution and have shown that a similar benzo-substituted derivative (6) displays remarkable affinity for oligophosphates. Furthermore, 5-4H and its protonated [36]aneNg04 relative have recently been shown to efficiently catalyze a-proton exchange in malonate ions (rate enhancements of 1.4 x 1(9 and 1.8 x 10, respectively) at neutral pH. ... 

A large number of bivalent and trivalent cations were utilized as catalysts in this reaction. The effectiveness of the cation as a catalyst strictly paralleled its power of forming a complex with the malonate ion, a model for the transition state of the reaction. This parallelism strikingly shows that the ability of a metal ion to catalyze this process depends on its ability to complex with the transition state. 

What is needed in the synthesis of C is a two-carbon nucleophile (or its equivalent) which is less basic titan an enolate so elimination is not competitive. If product C is recognized as an acetic acid derivative, then the following analysis can be made. A malonate ion used as the carbon nucleophile is much less basic than a simple ester enolate and hence undergoes substitution readily but does not promote elimination effectively, particularly in secondary systems. 

Whereas it has been demonstrated that both malonate ions and thiolate ions can catalyze the free radical chain addition reaction of perfluoroalkyl iodides to olefins [289,290], under appropriate conditions one can obtain products deriving from substitution in such processes. Following early work carried out photo-lytically in liquid ammonia, recent reports have indicated that good yields of substitution products can be obtained in polar solvents at room temperature, without irradiation [291-296]. 

Reactions with stabilized enolate species such as malonate ions also lead to alkylation, but because of the requisite basic conditions, the initial alkylation products are subsequently converted to secondary products [289]. 

Sodium salt of malonate carbanions are known to react quantitatively with the living ends of poly(vinyl ether)s to give a stable carbon-carbon bond [45]. This reaction was performed to end-functionalize living poly(vinyl ether)s with a vinyl ether polymerizable end group using the functional malonate ion 36 [73,89]. 

Several carbanions, such as acetone enolate or diethyl malonate ions, failed to react with neopentyl bromide in liquid ammonia under irradiation. In DM SO dehalogenation (100%) was the main reaction of 97 in the presence of the enolate ion of the acetone (27a) whereas with the enolate ion of acetophenone (27b) it gave the substitution product in 55% yield (equation 75). This reaction showed slight inhibition by p-DNB or TEMPO157. 

Several halopyridines bearing not only CN186, but also CF3 substituents, react with malonate ions in liquid ammonia. The results with 2-chloropyridines (142) depend on the position of the CF3 group as shown in equation 94. With 3-CF3 there was no reaction188. 

Nitrosylcarbonyhron complexes, [Fe(CO)3(NO)] and Fe(CO)2(NO)2, are capable of catalyzing the substitution of allyhc chlorides, formates, acetates, and carbonates by malonate ion. The attack on substituted substrates goes with retention of double bond stereochemistry, with high retention of stereochemistry at the substituted carbon atom, and with... 

The highest value of feMA is obtained for M"+ = Cu2+. Less active catalysts than Cu2+ are the ions Ni2+, Zn2+ and Co2+. The sequence of the catalytic powers of the metal ions is identical with that found by Irving and Williams [268] for the equilibrium constants of complex formation. There is a linear relationship between log feMA and log i Mmaionate the logarithm of the complex formation constant of Mn+ with malonate ion. 

The association of four clathrochelates (Table 29) with perchlorate, sulphate, and malonate ions was detected from their CD spectra [118], The A-[Co(diNOsar)]2+ and A-[Co(NOMEsar)]3+ cations formed 1 1 associates with perchlorate cations in water. The association constant of the former cation with perchlorate ion was determined to be 0.54. The association constant for the perchlorate salt of the latter cation was not obtained, but it is expected to be lower than that for the A-[Co(diNOsar)]2+ cation. The 1 1 association constants for clathrochelate cobalt(III) cations with sulfate and malonate anions were determined from the CD spectra using a wavelength at which the CD intensity was not affected by the perchlorate anion concentration. The constants obtained are listed in... 

Thus five steps are involved in the reaction between a hexaaquachromium(III) ion and an o,o -dihydroxydiarylazo compound at low pH to form the 1 1 chromium complex dyestuff three ligand replacement reactions and two ionization stages. Studies with other ligands lead to the conclusion that the probable rate-determining step is replacement of the first of the six coordinated water molecules in the highly symmetrical hexaaquachromium(III) ion by one of the donor functions of the ligand. For example, it has been shown that the rate of reaction between the hexaaquachromium(III) ion and the bidentate oxalate or malonate ions to form monochelate... 

With soft nucleophiles, steps a and b of Scheme 12.10b are the same as those in Scheme 12.10a. The crucial difference between the two pathways originates in the next steps. Soft nucleophiles attack the T 3—allyl complex anti to the metal (step c, Scheme 12.10b), which results in another inversion of configuration. This is followed by decomplexation (step d), which occurs with retention of configuration. Overall, therefore, two inversions followed by retention result in a net retention of configuration. Equations 12.26 and 12.27 illustrate the stereochemistry attendant to the reaction of diastereomeric allylic acetates with malonate ion.57... 

Halogenation of A(-methyl groups is possible under radical conditions <93ZOBI879>. Nitromethyl substituents are subject to Srn 1 substitution under photolytic stimulation, and the exocyclic nitro group can also be replaced by malonate ion, or reduced to hydrogen by tributyltin hydride <94BSF200>. 

The following sequence of dipositive metal ions shows a decreasing effect on the rate of decarboxylation of oxaloacetic acid Cu(II), Zn(II), Co(II), Ni(II), Mn(II), Cu(II) (91). The rate constants for these decarboxylations approximately parallel the formation constants of the corresponding metal oxalates. A similar result was found in the decarboxylation of acetonedicarboxylic acid in the presence of certain transition metal ions the decarboxylation rates paralleled the formation constants of the metal malonates (170). These parallelisms indicate that the effectiveness of a metal ion in these decarboxylation reactions depends on its ability to chelate with the oxalate ion and the malonate ion, which resemble the transition states of the oxaloacetic and acetonedicarboxylic acids, respectively. 

Other Reactions of Unsaturated Steroids.—A review on organopalladium intermediates includes several steroidal examples. A mechanistic study of the formation of the 7r-allyl palladium complex (65) from the corresponding 3-oxocholest-4-ene led to the conclusion that initial 7r-complexing was rate limiting. Reactions of a series of similar ir-allyl palladium complexes (66)—(68) with dialkyl malonate ion gave the 3-oxo-A -6/S-yl malonates (69)—(71) respec-... 

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