A comparative study on the thermal decomposition of some transition metal carboxylates

Thermal decomposition of transition metal malonates, MCH₂C₂O₄?xH₂O and transition metal succinates, M(CH₂)₂C₂O₄?xH₂O (M=Mn, Fe, Co, Ni, Cu, Zn) has been studied employing TG, DTG, DTA, XRD, SEM, IR and Mössbauer spectroscopic techniques. After dehydration, the anhydrous metal malonates and succinates decompose directly to their respective metal oxides in the temperature ranges 310–400 and 400–525°C, respectively. The oxides obtained have been found to be nanosized. The thermal stability of succinates have been found to be higher than that of the respective malonates.     

N,N′-Dioxide-scandium(III) complex catalyzed highly enantioselective Friedel-Crafts alkylation of indole to alkylidene malonates

A highly efficient enantioselective Friedel-Crafts alkylation of indoles with alkylidene malonates has been developed using chiral N,N′-dioxide L4-scandium(III) complex as the catalyst, giving the corresponding products in high yields with excellent enantioselectivities (up to 99% yield and 95% ee). The product 3a was facilely converted into several interesting compounds, such as tryptamines, indolepropionic acids and β-carbolines. It is noteworthy that the seven-membered β-carboline-like compound has been synthesized for the first time. Based on the crystal structure of the chiral N,N′-dioxide L10-scandium(III) complex, the proposed transition state and possible catalytic cycle were presented to elucidate the reaction mechanism.     

Diastereoselective addition of silyl- and stannyl metals to γ-alkoxy-alkylidene malonates

Stereochemical control of the addition of silyl- and stannyl metals to chiral γ-alkoxy-alkylidene malonates proved to be dependant on the nature of the counter ion and of the solvent but in an unpredictable way.     

[3+3] Cyclocondensation of 1-alkyl-substituted 3,4-dihydroisoquinolines with 2-aminomethylenecycloalkane-1,3-diones or aminomethylene malonates: A novel annelation reaction in the series of cyclic Schiff's bases

A new approach to the construction of polycyclic skeletons of fused azines with nitrogen at the bridgehead based on a novel reaction of cyclic Schiff's bases (1-alkyl-substituted 3,4-dihydroisoquinolines) with α-aminomethylenecarbonyl compounds (2-aminomethylene-cyclohexane-1,3-diones or aminomethylenemalonic ester) was developed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1358–1360, July, 1997.     

Nichtsteroide Entzündungshemmer, 4 Umlagerungen von Heterocyclen, 11 Ketenoide Umlagerung und Oxidation von 2-Pyronen zu 1,4-Naphthochinon-5-alkansäuren

Fused 2-pyrones4, obtained by the thermal condensation of ketones1 with reactive malonates2, rearrange above 200°C to yield condensed dihydroxynaphthalines5. The latter compounds can be oxidized to give 3-hydroxy-1,4-naphthoquinone-5-alkanoic acids. The reaction of ketone8 with magic malonates2 or chlorocarbonyl ketene9 affords the pyrones11 in low yields. The 2-pyrones11 could not be rearranged to13; a possible explanation for this behaviour is presented.

Herrn Prof. emer. Dr.E. Ziegler, der vor 30 Jahren erstmals die ketenoide Reaktionsweise von Malonsäurederivaten beschrieb [16], in Dankbarkeit und Freundschaft gewidmet.     

Silicon-controlled Carbon–Carbon Bond Formation and Cyclization between Carbonyl Compounds and Allyltrimethylsilane

The effect of silicon on C–C bond formation between carbonyl compounds and allyltrimethylsilane was investigated. Treatment of 1,3-diketones, β-ketoesters or malonates with allyltrimethylsilane in the presence of ceric ammonium nitrate (CAN) in methanol produced the corresponding allylated products. Furthermore, introduction of Mn(OAc)₃ · 2H₂O into those reactions for replacement or assistance of CAN afforded silicon-containing cyclopentanes in 51–75% yields. A sequential process involving allylation, free-radical cyclization and elimination was also developed by use of CAN/Mn (OAc)₃ · 2H₂O/Cu(OAc)₂ · H₂O. Accordingly, β-ketoesters or malonates were allowed to react with allylsilanes in acetic acid to give silicon-containing cyclopentanes with an exo methylene unit in 52–71% yields. These reactions involved carbocationic and carboradical intermediates, of which formation and chemical activities were controlled by a β-silyl group. © 1997 by John Wiley & Sons, Ltd.     

Thermal Decomposition of Strontium and Barium Malonates

The thermal decomposition of strontium and barium malonates has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DTA, DSC, XRD and IR spectroscopic techniques. DSC of these malonates has been recorded both in oxygen and nitrogen atmospheres. The decomposition is a single step process and the end product formed is carbonate. The energy of activation and frequency factor values for the decomposition of strontium malonate are 547 kJ mol⁻¹ and 10⁴¹ s⁻¹ respectively. The activation energy and frequency factor values for isothermal dehydration of barium malonate sester-hydrate are 57–111 kJ mol⁻¹ and 10⁷–10¹² s⁻¹ respectively and the corresponding values for decomposition from DSC are 499.5 kJ mol⁻¹ and 10⁴⁴ s⁻¹ respectively. The higher thermal stability of strontium malonate as compared to that of barium salt is ascribed to its being anhydrous so that decomposition proceeds without restructuring. Their thermal stabilities have also been compared with that of respective oxalate salts. This revised version was published online in July 2006 with corrections to the Cover Date.     

Electrocatalytic transformation of dialkyl malonates and arylidene- or alkylidenemalononitriles into dialkyl esters of 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylic acids

Electrolysis of alcoholic solutions of dialkyl malonates and arylidene- or alkylidenemalononitriles in the presence of NaBr in an undivided cell gave dialkyl esters of 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylic acids in 60–90% yields. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1547–1552, July, 2005.     

微波作用下亚烃基丙二酸亚异丙酯的合成

报导了微波辐射下丙二酸亚异丙酯与羧基化合物进行了Ｋｎｏｅｖｅｎａｇｅｌ缩合反应，高产率地合成了亚烃基丙二酸亚异丙酯。