Copper-Catalyzed Coupling of (E)-Bromostilbene with Phenols/Azole: ESI-MS Detection of Intermediates by Using an Ionically-Tagged Ligand

• Published in: Advanced synthesis & catalysis 2012-05, Vol.354 (8), p.1429-1436
• Main Authors: Limberger, Jones, Leal, Bárbara C., Back, Davi F., Dupont, Jairton, Monteiro, Adriano L.
• Format: Article
• Language: English
• Subjects: Activation; Chemistry; copper; cross-coupling; ESI-MS; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; ion-tagged ligand; Kinetics and mechanisms; Noncondensed benzenic compounds; Organic chemistry; Preparations and properties; Reactivity and mechanisms; vinylation
• ISSN: 1615-4150; 1615-4169
• DOI: 10.1002/adsc.201100925

A system based on copper/1,10‐phenanthroline efficiently promotes the coupling between phenols or pyrazole with (E)‐bromostilbene. (E)‐1‐Aryloxy‐1,2‐diphenylethenes were obtained from the coupling with phenols in good to excellent yields (69–90%). The exception was the reaction involving a phenol containing an electron‐withdrawing cyano group that required a longer reaction time and gave only 49% yield. Kinetic studies indicated the participation of the vinyl halide in the rate‐determining step. Under the conditions employed, the activation of the vinyl halide via a radical pathway was discarded using a radical scavenger test. By using an ionically‐tagged 1,10‐phenanthroline derivative as the ligand, various copper‐based ions were detected through ESI(+)‐MS. These ions suggested that formation of the active species [phenCuOAr(HOAr)2] precedes the vinyl halide activation.