Coupling of carbanions. Formation of succinic acid derivatives

Reaction of α-carbanions of lithium acylates with 1,2-dibromoethane

“…The aqueous layer was separated, and the organic layer was analyzed by gas-liquid chromatography and mass spectrometry. 1 Н and 13 C NMR spectral parameters of the products coincided with the reference data [4].…”

“…Metalated CH-acids (esters, nitriles, acylates, diphenylmethane, etc) are known to react with alkyl halides and dihalides (the latter containing distant CH 2 Hlg) groups via the nucleophilic substitution of the halogen with the carbanion [1]. The interaction involving vicinal alkyl dihalide follows a more complicated path yielding products of the halogen nucleophilic substitution as well as of oxidative dimerization of carbanions [1,2].…”

“…The interaction involving vicinal alkyl dihalide follows a more complicated path yielding products of the halogen nucleophilic substitution as well as of oxidative dimerization of carbanions [1,2]. The reaction direction depends on structure of the carbanion, the 1,2-dihaloalkane, and the halogen nature [1,2].…”

X-philic reactions

“…21 For synthetic purposes this method has been modified by the use of metallic (Li, Na, or K) derivatives of the carbanion and generation in situ of the second partner, namely a halogeno compound, via the halogenophilic pathway, as shown in eq 50.126 NaNH2 (50) The anions of acetonitrile, benzhydryl, and benzyl derivatives have been used to obtain the corresponding substituted ethanes, and CC14, 1,2-dihalides (e.g., 2,3dibromo-2,3-dimethylbutane), and polyhalides (e.g., hexachloroethane) may play the role of halogen-containing component for these couplings. 126,[194][195][196][197][198][199] Such dimerizational processes seem to be potentially useful synthetically, especially in view of the modern development of the chemistry of carbanions.…”

Conversions of .alpha.-methyl to .alpha.-methylene-.gamma.-lactones. Synthesis of two allergenic sesquiterpene lactones. (-)-Frullanolide and (+)-arbusculine B

“…The carbanion A' (Chart II), unlike that of the model system 3, is very unstable, and could only be obtained satisfactorily by treatment of 13 with excess triphenylmethyllithium in 1,2-dimethoxyethane in the presence of IV,N,N',jV'-tetramethylethylenediamine (TMEDA). Carbanion A', when quenched with 1,2-dibromoethane, afforded a single «-bromo lactone 15 in ca. 50% yield.…”