Biological catalysts utilize steric and electronic modifications to attain a remarkable degree of substrate specificity. One mechanism by which enzymes finely tune reactivity is through allosteric regulation, in which the enzyme responds to the presence of a distant activator, which typically induces conformational changes that alter enzyme activity. Although tuning reactivity via chemical triggers is common in biological systems, there are currently few analogs in synthetic systems. We chose a strategy to vary electrophilicity using a remote chemical switch, in which second-sphere Lewis acid binding modulates electrophilicity in the first coordination sphere. Lewis acid coordination occurs at a remote ligand site, allowing for systematic studies of metal complexes with variable electrophilicity but conserved ligand structures. Platinum(II) complexes featuring remote nitrogen donor sites have been prepared, and binding of Lewis acidic boranes at these positions has been demonstrated. Biaryl reductive elimination is accelerated over 50,000-fold for the more electron-deficient, Lewis-acid-bound platinum complexes.

Dramatic acceleration of biaryl reductive elimination from a platinum complex using a remote Lewis acid trigger

246th National Meeting (2013)

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