Reactivity of mixed organozinc and mixed organocopper reagents: 5-A kinetic insight to compare the transfer ability of the same group in copper catalyzed alkylation of mixed and homozincates

Erdik E., Serdar E. Z.

Journal of Organometallic Chemistry, vol.703, pp.1-8, 2012 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 703
  • Publication Date: 2012
  • Doi Number: 10.1016/j.jorganchem.2011.11.027
  • Journal Name: Journal of Organometallic Chemistry
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1-8
  • Keywords: Kinetics of catalytic cuprate, Mixed triorganozincate, Organozincate derived diorganocuprate, Residual group, Transferable group
  • Ankara University Affiliated: Yes

Abstract

A detailed kinetic investigation and activation parameters are reported for copper catalyzed coupling reaction of mixed zincate, n-BuPh2ZnMgBr and homozincate, Ph3ZnMgBr with n-pentyl bromide in THF at 25-65 °C. An empirical rate law can be expressed as rate = k[zincate]0 [alkyl bromide]1 [CuI]1. The reaction rate of transferable phenyl group in mixed catalytic cuprate, n-BuPhCuMgBr derived from mixed zincate is higher than the rate of catalytic homocuprate Ph2CuMgBr derived from homozincate. A catalytic cycle and the mechanism which accommodates the kinetic data and activation parameters is given. These results show that the reaction rate of transferable group changes depending on the residual group in the reactions of mixed diorganocuprates and also provide a kinetic support for the commonly accepted hypothesis regarding the dependence of the R 1 group transfer ability on the strength of R2-Cu bond in reactions of R1R2CuMgBr reagents. © 2011 Elsevier B.V. All rights reserved.