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Promoting Difficult Carbon–Carbon Couplings: Which Ligand Does Best?
Author(s) -
Gioria Estefanía,
del Pozo Juan,
MartínezIlarduya Jesús M.,
Espinet Pablo
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201607089
Subject(s) - xantphos , ligand (biochemistry) , chemistry , stereochemistry , coupling (piping) , carbon fibers , hydrolysis , medicinal chemistry , catalysis , palladium , organic chemistry , mathematics , materials science , biochemistry , algorithm , composite number , receptor , metallurgy
Abstract A Pd complex, cis ‐[Pd(C 6 F 5 ) 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 Pd 0 L. Complex 1 ranks the coupling ability of some popular ligands in the order P t Bu 3 > o ‐TolPEWO‐F≈ t BuXPhos>P(C 6 F 5 ) 3 ≈PhPEWO‐F>P( o ‐Tol) 3 ≈THF≈ t BuBrettPhos≫Xantphos≈PhPEWO‐H≫PPh 3 according to their initial coupling rates, whereas their efficiency, depending on competitive hydrolysis, is ranked t BuXPhos≈P t Bu 3 ≈ o ‐TolPEWO‐F>PhPEWO‐F>P(C 6 F 5 ) 3 ≫ t BuBrettPhos>THF≈P( o ‐Tol) 3 >Xantphos>PhPEWO‐H≫PPh 3 . This “meter” also detects some other possible virtues or complications of ligands such as t BuXPhos or t BuBrettPhos.