Phosphine ligands allylic-phosphorus reactions

Cyclometallation of phosphine ligands is a pathway that can deactivate catalysts. Addition of aryl C-H bonds is most favorable, and addition of the primary C-H bonds in methylphosphines is more favorable than addition of the methylene C-H bonds in higher alkylphosphines. Catalytic reactions initiated by compounds containing cyclometallated phosphorus ligands as stable and convenient precursors to active catalysts have been reported, some of which are shown in Figure 6.4. Less common are catalysts that become activated by cyclometallation one example that catalyzes allylic substitution is shown in Figure 6.5. ... 

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