ChemInform Abstract: Pd(OAc)₂/p‐Benzoquinone‐Catalyzed Anaerobic Electrooxidative Homocoupling of Arylboronic Acids, Arylboronates and Aryltrifluoroborates in DMF and/or Water.

Abstract

Polyphenyl derivatives Q 0700Pd (OAc)2/p-Benzoquinone-Catalyzed Anaerobic Electrooxidative Homocoupling of Arylboronic Acids, Arylboronates and Aryltrifluoroborates in DMF and/or Water. -The title electrooxidative homocoupling of arylboronic acids, -boronates or aryl trifluoroborates can also be carried out in water or aqueous DMF solution using sodium sulfate as electrolyte although best results are achieved in DMF. The method avoids the use of stoichiometric amounts of chemical oxidant and, thus, the formation of side products. -(AMATORE*, C.; CAMMOUN, C.; JUTAND, A.; Eur. J. Org. Chem. 2008, 27, 4567-4570; Dep. Chim., Ec. Norm. Super., Univ. P. et. M. Curie, F-75231 Paris, Fr.; Eng.) -Mischke 04-074

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…560,561 Around the same time, Jutand and coworkers reported a similar electrochemical approach to boronic acid dimerization with benzoquinone as the mediator. 562 Another recent application of the Pd(OAc) 2 /TEMPO system is the cross coupling between terminal alkynes and aryl boronic acids (Figure 37A, middle). 563 In this case, a silver anode is used which allows the formation of silver acetylides; coupling was also observed using a copper anode albeit in lower yields, while the use of Pt anode led to little product formation (≤5%).…”

Electrochemical Arylation Reaction

“…35−37 For example, in one electrooxidative method by Amatore et al an anaerobic protocol using Pd(II) species as catalyst was developed. 35 It is used with a catalytic amount of p-benzoquinone serving as ligand for Pd(0) as well as redox catalyst for the Pd(0) species, which is generated in situ. p-Hydroquinone is then oxidized at the anode back to pbenzoquinone, as shown in Scheme 10.…”

“…Instead of p-benzoquinone the use of TEMPO as organic mediators was successfully applied as well. 36,37 When using p-benzoquinone as mediating system constant potential electrolytic conditions (+ 0.75 V) using a carbon cloth anode and a saturated calomel reference electrode were applied 35 whereas for TEMPO constant current conditions with low current densities (3.3 mA/cm 2 ) at platinum electrodes were employed. 36,37 In both protocols the desired homocoupling products can be obtained in good yields with electronwithdrawing and electron-releasing substituents.…”

Kinetic studies of copper-catalyzed homocoupling reactions of arylboronic acids in aqueous micellar media

“…Transition-metal-catalyzed couplings, such as the Suzuki reaction, have made significant advances in the synthesis of symmetrical and unsymmetrical biphenyls (Marion et al, 2006, McGlacken andBateman, 2009). The Pd(II)-catalyzed homocoupling of boronic acids has been widely researched (Jin et al, 2009, Mitsudo et al, 2009, Mu et al, 2009, Amatore et al, 2008, Cicco et al, 2010, Mitsudo et al, 2008, Prastaro et al, 2010. The kinetics of palladium-catalyzed aerobic oxidative homocoupling reaction of phenylboronic acids in an aqueous micellar medium (Othman, 2011).…”

“…The stability of the Pd(II)--CD catalyst and its catalytic activity in the aerobic homocoupling reaction of phenylboronic acid were investigated (Othman, 2020). These catalytic techniques, however, have some limits, such as (i) Palladium is costly, and additional ligands are frequently needed (Jin et al, 2009, Zhou et al, 2007, Yamamoto, 2007, Yamamoto et al, 2006, (ii) certain oxidants are employed to restore the catalyst (Amatore et al, 2008, Cheng et al, 2007, Mitsudo et al, 2009, Kabalka and Wang, 2002, Parrish et al, 2002, Klingensmith and Leadbeater, 2003, Mitsudo et al, 2008, (iii) to obtain high yields of biphenyls, a strong base must be added (Wong and Zhang, 2001, Jin et al, 2009, Yadav et al, 2007, Burns et al, 2007 and (iv) to complete the reaction high temperature is needed (Amatore et al, 2008, Cheng et al, 2007, Prastaro et al, 2010. Copper has recently been discovered to be a low-cost, environmentally friendly metal catalyst for the production of useful organic compounds.…”