Unveiling the Role of Base and Additive in the Ullmann-Type of Arene-Aryl C-C Coupling Reaction

Manjaly J. Ajitha, Fathima Pary, Toby L. Nelson*, Djamaladdin G. Musaev

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

The mechanism of Ullmann-type biaryl formation between benzo-[1,2-b:4,5-b′]dithiophene-1,1,5,5-tetraoxide (BDTT) and iodobenzene (ArI) was computationally studied in the presence of CuI, phenanthroline (Phen), K3PO4 (as a base), and Ag2CO3 (as an additive). It is shown that base and additive play critical roles in each step of the reaction, such as (a) the I-to-base exchange in complex (Phen)CuI, (b) substrate deprotonation via the acid-base mechanism, and (c) Ar-I activation and DBT-Ar coupling. It is shown that (a) the presence of sulfonyl oxygens in DBT is essential - it plays an anchoring role and brings substrate and base closer to each other. In the presence of K3PO4 and in the absence of additive Ag2CO3, the Ph-I activation and C-C coupling occurs via a Cu-mediated nucleophilic substitution mechanism and requires a significant free energy barrier. However, the addition of Ag2CO3 to the reaction mixture not only accelerates the DBT and PhI coupling by reducing the rate-limiting Ph-I activation barrier but also switches the mechanism of the reaction from a Cu-mediated nucleophilic substitution to a Ag(I)-promoted oxidative addition-reductive elimination. These findings are important for development of the next generation reaction conditions for Ullmann-type of coupling reactions.

Original languageEnglish (US)
Pages (from-to)4829-4837
Number of pages9
JournalACS Catalysis
Volume8
Issue number6
DOIs
StatePublished - Jun 1 2018

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation under the CCI Center for Selective C−H Functionalization (CHE-1700982). We gratefully acknowledge NSF MRI-R2 grant (CHE-0958205 for D.G.M.) and the use of the resources of the Cherry Emerson Center for Scientific Computation, as well as Oklahoma State University Division of Institutional Diversity. Authors are thankful to Dr. Brandon Haines for help provided during the manuscript preparation.

Funding Information:
This work was supported by the National Science Foundation under the CCI Center for Selective C-H Functionalization (CHE-1700982). We gratefully acknowledge NSF MRI-R2 grant (CHE-0958205 for D.G.M.) and the use of the resources of the Cherry Emerson Center for Scientific Computation, as well as Oklahoma State University Division of Institutional Diversity. Authors are thankful to Dr. Brandon Haines for help provided during the manuscript preparation.

Publisher Copyright:
© 2018 American Chemical Society.

Keywords

  • additive effect
  • Ag(I)-promoted oxidative addition-reductive elimination
  • Cu-mediated nucleophilic substitution
  • DFT studies
  • Ullmann-coupling

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry

Fingerprint

Dive into the research topics of 'Unveiling the Role of Base and Additive in the Ullmann-Type of Arene-Aryl C-C Coupling Reaction'. Together they form a unique fingerprint.

Cite this