Ru-Catalysed Alkylation of Secondary Phosphines

The fact that the reactions proceed with benzyl chlorides at — 30 °C with good yields highlight the remarkable nucleophilic character of the ruthenium catalyst. Para-substituted electron-donating benzyl chlorides are well tolerated 

With the complex containing (R)-MeO-BiPHEP the results with mono- and dibenzylic substrates were similar to those obtained with complex 94 (Table 6.14) but at room temperature instead of at 30 °C. Interestingly, in contrast to 94 it was found that the complex with the phosphine (i )-DIFLUORPHOS is active in the phosphination of aliphatic substrates (Table 6.15).  

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The three reactions are likely to have phosphido complexes as intermediates. Pt-, Pd- and Ln-catalysed hydrophosphination of activated alkenes and Pd-catalysed phosphination of aryl halides (a cross-coupling reaction) have been known for some time whereas Pt and Ru-catalysed alkylation of secondary phosphines are more recent. 

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