Metal reduction hydrocarbons

Alkali metal reduction is a widely employed method for the preparation of radicals derived from various classes of conjugated compounds such as hydrocarbons, heterocycles, nitro compounds, quinones, and nitriles. For... 

Alkali metals in liquid ammonia represent the most important class of the so-called dissolving-metal reductions of aromatics. First described in 1937, it is a highly efficient and convenient process to convert aromatic hydrocarbons to partially reduced derivatives.201 The recognition and extensive development of this electron-transfer reduction came from A. J. Birch,202,203 and the reaction bears his name. 

The lithium metal reduction of 7r-conjugated hydrocarbons and fullerenes... 

For reviews on alkali metal reduction of polycyclic hydrocarbons see ... 

Tetraene 433 was prepared in two steps from the readily available Schroder hydrocarbon 4 0.395 Woelm activity I neutral alumina caused rearrangement of 430 to a mixture of 431 and 432. Thermolysis of 431 at 380 °C in a flow system afforded 4JJ.390 Dissolving metal reduction of433 did not give a rise to a spectroscopically recognizable dianion species. Electrochemical measurements were equally disappointing. 

The approach employed for the preparation of nortriquinacene derivatives was based upon ring contraction of the a-diazocarbonyl derivative and subsequent degradation of the epimeric carboxyl derivatives (Scheme 67).393 All attempts to deprotonate hydrocarbon 445 have proven unsuccessful. Metal reduction studies on 444 and the related chlorides also failed to provide evidence for formation of a stabilized carbanion. Calculations agree with the absence of significant homoconjugation in 429. For example, this species is predicted to have a pyramidal rather than a trigonal anionic carbon.393 In addition, exo-methylene derivatives of nortri-... 

Reduction with alkali metals The solvents used for alkali metal reductions include hydrocarbons, ethers and, most commonly, liquid ammonia. Alcohols may also be used, but usually as co-solvents, since they react vigorously with these metals. Aldehydes are not usually reduced in this manner, because they react with ammonia to form unreactive imine condensation products. 

In order to accomplish a total dehalogenation to hydrocarbons, dissolving metal reductions are most commonly employed. Cyclopropyl chlorides and bromides are satisfactorily reduced by alkali metal in alcohoF or in liquid ammonia. However, the fluorides are usually resistant to the hydrogenolysis. gem-Difluorides have been... 

Other anion-radicals containing the thiophene heterocycle in an otherwise hydrocarbon molecular environment and whose ESR spectra have been analyzed are 110 (for which hyperfine splittings are given in gauss), the anionic counterpart of 94, and the anion-radical of 963 2,343. thieno[2,3-ZjJthiophene (111) failed to give a persistent radical by alkali metal reduction. 

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