Computational Characterization of the Role of the Base in the Suzuki−Miyaura Cross-Coupling Reaction

Abstract

The role of the base in the transmetalation step of the Suzuki-Miyaura cross-coupling reaction is analyzed computationally by means of DFT calculations with the Becke3LYP functional. The model system studied consists of Pd(CH=CH2)(PH3)2Br as the starting catalyst complex, CH2=CHB(OH)2 as the organoboronic acid, and OH- as the base. The two main mechanistic proposals, consisting of the base attacking first either the palladium complex or the organoboronic acid, are evaluated through geometry optimization of the corresponding intermediates and transition states. Supplementary calculations are carried out on the uncatalyzed reaction and on a process where the starting complex is Pd(CH=CH2)(PH3)2(OH). These calculations, considered together with available experimental data, strongly suggest that the main mechanism of transmetalation in the catalytic cycle starts with the reaction of the base and the organoboronic acid.

Roles of Bases in Transition-Metal Catalyzed Organic Reactions

“…Suzuki 偶联反应在没 有碱的参与时是很难发生的. 在该反应中, 碱最重要的 作用是促进转金属反应的进行(图 17) [33] . 反应中碱的影 响不仅取决于碱(负离子)的强弱, 而且也与阳离子的性 质有关.…”

Pd-catalyzed Suzuki cross-Coupling reaction of bromostilbene: insights on the nature of the boron Species

“…11 Recently, theoretical studies strongly suggest that an organoborate [ArB(OH) 3 ] -is involved in the transmetalation step. [12][13][14] The fact that trihydroxyarylborates can be applied for the base-free Suzuki reaction with aryl halides is a strong experimental evidence. 8 Our results for the different boron species in the presence and absence of base (see Table 1) also goes in the same direction and our next step was to identify the boron species present during the coupling reaction.…”

ChemInform Abstract: Practical Aspects of Carbon—Carbon Cross‐Coupling Reactions Using Heteroarenes

“…In the first one, the base replaces the halide on the palladium complex and facilitates the intramolecular transmetalation (path I). 94 Alternatively, the boronate interacts with the metal center and transmetalates in an intramolecular fashion (path II). 95 The selective functionalization of aryl and heteroaryl compounds with boron species is an important synthetic task, and the efficiency of this step plays an important role in the decision making for the use of the Suzuki-Miyaura coupling.…”