摘要：

Dipotassium cyclooctatetraenide in tetrahydrofuran reacts with dichlorophenylphosphine to give I, which upon warming isomerizes to II. Upon pyrolysis II rearranges to an isomeric substance II′, shown to be epimeric with II at the phosphorus nucleus. The structures of these substances were proven by analysis of their proton nmr spectra with the aid of phosphorus and proton decoupling. The formation of I and its rearrangement to II are stereospecific reactions. The epimerization of II to II′ in chloroform solution is catalyzed by HCl. (No phosphiranes, bridged phosphines, rearrangements of bicyclo[6.1.0]nonatrienes to bicyclo[4.2.1]nonatrienes, or acid-catalyzed phosphine inversions were previously known.) With methyl iodide the phosphines II and II′ form methiodides, II-M and II′-M, and with hydrogen peroxide phosphine oxides, II-O and II′-O, both stereospecifically and presumably with retention of configuration. With air they both form the oxide II′-O. Palladium chloride complexes of II and II′ were also prepared, and that of II′ was used to purify the phosphine. Mechanisms for the acid-catalyzed inversion of configuration are discussed. Although II and II′ differ only in stereochemistry, their 31P chemical shifts differ by 65 ppm. The 31P chemical shift of compound I (+181 ppm relative to 85% H3PO4) is higher than that of any trialkylphosphine known.

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