o-Hydroxyarylphosphines and diphosphines: metallation-rearrangement versus P---O reduction of o-halogenoaryloxyphosphines by sodium |
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Authors: | Joachim Heinicke Renat Kadyrov |
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Institution: | Institut für Anorganische Chemie, Ernst-Moritz-Arndt-Universität Greifswald, Soldtmannstr. 16, D-17487, Greifswald, Germany |
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Abstract: | o-Bromo- and o-chloroaryloxyphosphines 1 may react with sodium in two competing ways: (i) metal halogen exchange followed by rapid intramolecular 1,3-rearrangement to give sodium o-hydroxylato-arylphosphines 2, later converted to their OSiMe3 derivatives 3, and (ii) reductive cleavage of the P---O bond to give diphosphines 4 or phosphides. The o-metallation is preferred with the more reactive bromides and bulky phosphino substituents or screened P---O bonds by substituents at 6-position. The reduction is favoured in the case of the less reactive aryl chlorides, small alkyl and flat phenyl substituents at phosphorus. Mixtures of meso- and rac-diphosphines are formed from asymmetric derivatives ArOPRR′. The meso-isomer of 1,2-di(tert-butyl)-1,2-diphenyldiphosphine is preferred. |
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Keywords: | Hydroxyarylphosphines Metallation Rearrangement Diphosphines Sodium Ligand |
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