Carbanions compounds

You have already had considerable experience with carbanionic compounds and their applications in synthetic organic chemistry The first was acetyhde ion m Chapter 9 followed m Chapter 14 by organometallic compounds—Grignard reagents for example—that act as sources of negatively polarized carbon In Chapter 18 you learned that enolate ions—reactive intermediates generated from aldehydes and ketones—are nucleophilic and that this property can be used to advantage as a method for carbon-carbon bond formation... 

VII. ENANTIOSELECTIVE ADDITION OF ACHIRAL CARBANIONIC COMPOUNDS IN THE PRESENCE OF (-)-SPARTEINE... 

A different and independent approach to determine the parameters of KC8 is made by conductivity measurements. The dissociation constant of carbanionic compounds displays no simple temperature dependence according to the van t Hoff equation as Worsfold and Bywater (32) and Szwarc (33) have already shown. When we assume two types of ion pairs, the experimentally measured dissociation constant is given by... 

The three major classes of nucleophilic carbon species are organometallic compounds, enolate derivatives and related carbanionic compounds, and neutral enol derivatives ... 

This chapter focuses the attention on the reactions of nonstabilized carbanionic compounds such as alkyl, vinyl, aryl, alkynyl metals, etc., and the chemistry of the stabilized system, i.e. allylic, propargylic or oxaallylic carbanions is presented in Volume 2 of this series. Electrophiles with C=X bonite which are discussed include aldehydes, ketones, epoxides, aziridines, acetals, orthoesters and imines, all of which turn into highly reactive electrophiles in the presence of Lewis acids. 

Using either the carbenoid compound 6 or the carbanionic compound 7 as a bulk base in large excess and 5 as catalyst (Scheme 11) gave the same stereoselectivity as the stoichiometric deprotonation of 2 with 5. 

Bases under PTC conditions promote both the conversion of acetylenes into allenes and the isomerisation of double bonds. H/D exchange can be easily obtained on every substrate capable of generating an intermediate carbanion. Compounds with... 

Mycophenolic acid was synthesized by a three-component coupling between the lactone 26, isoprene and dimethyl malonate (Eq. (23)) [47]. The reaction proceeds by the usual mechanism, with oxidative addition of the aryl halide to Pd(0) and subsequent insertion of isoprene into the Pd-aryl bond to give a t-allyl complex followed by nudeophilic attack by the malonate carbanion. Compound 27 was subsequently transformed to mycophenolic add. 

PART I Ylides and Carbanionic Compounds of Sulphur by E. Block... 

PART II Ylides and Carbanionic Compounds of Selenium and Tellurium... 

The major changes in the format and contents of this volume have been necessitated by economic considerations. Sulphur-containing heteroaromatic compounds which previously were included in these Reports and in the Reports on Aromatic and Heteroaromatic Chemistry are now covered in detail only in the new Reports, Heterocyclic Chemistry . The literature on these compounds has been reviewed up to March 1978 in Volume 5 of this series and thereafter in Volume 1 of the new series. Highlights of the literature of these compounds are given as Chapter 6 of this volume. The organization of the remainder of this volume is essentially the same as that of Volume 5 except that the section on the ylides and carbanionic compounds of selenium and tellurium has been considerably extended and the coverage of Chapter 3, Part III has been extended to include dithiocarbamates, xanthates, and trithiocarbonates. 

Although the 2-cyclopropylethyl carbanionic compounds (511) do not rearrange,the cyclopropylmethyl organometallics (513a) were shown to be intermediates in the degenerate rearrangements of the allylmethyl compounds... 

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