On the Compatibility of Ruthenium Metathesis Catalysts
with Secondary Phosphines
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Abstract
While
attempts to incorporate secondary phosphine ligands into
the first-generation Grubbs catalyst RuCl<sub>2</sub>(PR<sub>3</sub>)<sub>2</sub>(CHPh) (<b>GI</b>, R = Cy) were frustrated
by decomposition (for HPCy<sub>2</sub>) or bulk (for HP<sup><i>t</i></sup>Bu<sub>2</sub>), the mixed-phosphine complex <i>cis</i>-RuCl<sub>2</sub>(HP<sup><i>t</i></sup>Bu<sub>2</sub>)(PPh<sub>3</sub>)(CHPh) (<b>Ru-2b</b>) was
accessible in good yields from <b>GI</b>′ (R = Ph). Complex <b>Ru-2b</b> exhibited modest RCM activity. Ligand exchange with
pyridine revealed that this is due to preferential loss of the secondary
phosphine, rather than PPh<sub>3</sub>, from <b>Ru-2b</b>
