β-Arylation of Carboxamides via Iron-Catalyzed C(sp3)–H Bond Activation
摘要:
A 2,2-disubstituted propionamide bearing an 8-aminoquinolinyl group as the amide moiety can be arylated at the beta-methyl position with an organozinc reagent in the presence of an organic oxidant, a catalytic amount of an iron salt, and a biphosphine ligand at 50 degrees C. Various features of selectivity and reactivity suggest the formation of an organometallic intermediate via rate-determining C-H bond cleavage rather than a free-radical-type reaction pathway.
An iron(III) salt, (Z)-1,2-bis(diphenylphosphino)ethene or its electron-rich congener, (Z)-1,2-bis[bis(4-methoxyphenyl)phosphine]ethene, and a zinc(II) salt catalyze the arylation, heteroarylation, and alkenylation of propionamides possessing an 8-quinolylamide group with organoborate reagents in the presence of 1,2-dichlorobutane as oxidant at 70 °C. Stoichiometric experiments provided evidence for