Palladium(0)-Catalyzed, Copper(I)-Mediated Coupling of Boronic Acids with Cyclic Thioamides. Selective Carbon−Carbon Bond Formation for the Functionalization of Heterocycles

• Published in: Journal of organic chemistry Vol. 72; no. 12; pp. 4440 - 4448
• Main Authors: Prokopcová, Hana, Kappe, C. Oliver
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 08.06.2007; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Organic; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Kinetics and mechanisms; Organic chemistry; Physical Sciences; Preparations and properties; Reactivity and mechanisms; Science & Technology; CATALYSIS; ORGANOBORONIC ACIDS; COPPER-COMPLEXES; ARYLATION; ARYL IODIDES; LIBRARY GENERATION; MICROWAVE-ASSISTED SYNTHESIS; SUZUKI REACTION; EFFICIENT; ARYLBORONIC ACIDS; Copper II; Stoichiometry; Transition element complexes; Aromaticity; Molecular structure; Nitrogen heterocycle; Haloarene; Palladium complex; Selectivity; Cofactor; Organic sulfide; Functionalization; Thioamide; Cross reaction; Microwave irradiation; Copper I; Oxidation; Heterocyclic compound; Functional group; Ring size; Catalytic reaction; Suzuki coupling; Neutral medium; Cyclic compound; Desulfitation; Boron Organic compounds; Platinoid Complexes; Boronic acids
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo070408f

The palladium-catalyzed cross-coupling of cyclic thioamides with arylboronic acids in the presence of stoichiometric amounts of a copper(I) cofactor is described. The desulfitative carbon−carbon cross-coupling protocol is performed under neutral conditions and can be applied to a range of heterocyclic structures with embedded thioamide fragments. Successful carbon−carbon cross-coupling is independent of the ring size, aromaticity/nonaromaticity, the presence of additional heteroatoms, or other functional groups in the starting thioamide structure. Employing controlled microwave irradiation at 100 °C, most cross-couplings can be completed within 2 h and proceed in high yields. An advantage of using thioamides as starting materials is the fact that the system can be tuned to an alternative carbon−sulfur cross-coupling pathway by changing to stoichiometric copper(II) under oxidative conditions. Both types of thioamide cross-couplings are orthogonal to the traditional base-catalyzed Suzuki−Miyaura cross-coupling of aryl halides with boronic acids.