Promoting Difficult Carbon-Carbon Couplings: Which Ligand Does Best?

Estefanía Gioria; Juan Del Pozo; Jesús M Martínez-Ilarduya; Pablo Espinet

doi:10.1002/anie.201607089

Promoting Difficult Carbon-Carbon Couplings: Which Ligand Does Best?

Angew Chem Int Ed Engl. 2016 Oct 10;55(42):13276-13280. doi: 10.1002/anie.201607089.

Authors

Estefanía Gioria¹, Juan Del Pozo¹, Jesús M Martínez-Ilarduya¹, Pablo Espinet²

Affiliations

¹ IU CINQUIMA/Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, Paseo de Belén, 7, ES47071, Spain.
² IU CINQUIMA/Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, Paseo de Belén, 7, ES47071, Spain. espinet@qi.uva.es.

PMID: 27634585
DOI: 10.1002/anie.201607089

Abstract

A Pd complex, cis-[Pd(C₆ F₅ )₂ (THF)₂ ] (1), is proposed as a useful touchstone for direct and simple experimental measurement of the relative ability of ancillary ligands to induce C-C coupling. Interestingly, 1 is also a good alternative to other precatalysts used to produce Pd⁰ L. Complex 1 ranks the coupling ability of some popular ligands in the order P^t Bu₃ >o-TolPEWO-F≈tBuXPhos>P(C₆ F₅ )₃ ≈PhPEWO-F>P(o-Tol)₃ ≈THF≈tBuBrettPhos≫Xantphos≈PhPEWO-H≫PPh₃ according to their initial coupling rates, whereas their efficiency, depending on competitive hydrolysis, is ranked tBuXPhos≈P^t Bu₃ ≈o-TolPEWO-F>PhPEWO-F>P(C₆ F₅ )₃ ≫tBuBrettPhos>THF≈P(o-Tol)₃ >Xantphos>PhPEWO-H≫PPh₃ . This "meter" also detects some other possible virtues or complications of ligands such as tBuXPhos or tBuBrettPhos.

Keywords: cross-coupling mechanisms; homogeneous catalysis; palladium catalysis; phosphines; reductive elimination.

Publication types

Research Support, Non-U.S. Gov't