Carbanion Transition Metal-Mediated

Other types of heterofunctionalized cyclopropane derivatives used as starting materials in transition metal mediated conversions are acylcyclopropanes and similar systems. These systems, being electrophilic cyclopropanes, are opened by carbanion nucleophiles (e.g. cuprates, see Section l.B.2.1.3.) or nucleophilic transition-metal centers. In combination with siloxy groups, push-pull (capto-dative) substituted cyclopropanes are available as homoenolate precursors via Lewis acid mediated ring opening (see Section 1. B.2.1.4.).. This latter procedure has been used in tetrahydrofuran synthesis. 

Transition Metal-Mediated Carbanion Equivalent Formations... 

Many C(sp )—C(sp ) coupling reactions not transition metal-mediated involve the two electron oxidation of ethers or amines to oxocarbenium ions or iminium ions. These are then attacked in an ionic mechanism by in i dM-formed enolates or other carbanion nucleophiles to generate product. As such, they will not be covered in this review. 

During the coverage period of this chapter, reviews have appeared on the following topics reactions of electrophiles with polyfluorinated alkenes, the mechanisms of intramolecular hydroacylation and hydrosilylation, Prins reaction (reviewed and redefined), synthesis of esters of /3-amino acids by Michael addition of amines and metal amides to esters of a,/3-unsaturated carboxylic acids," the 1,4-addition of benzotriazole-stabilized carbanions to Michael acceptors, control of asymmetry in Michael additions via the use of nucleophiles bearing chiral centres, a-unsaturated systems with the chirality at the y-position, and the presence of chiral ligands or other chiral mediators, syntheses of carbo- and hetero-cyclic compounds via Michael addition of enolates and activated phenols, respectively, to o ,jS-unsaturated nitriles, and transition metal catalysis of the Michael addition of 1,3-dicarbonyl compounds. ... 

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