An Asymmetric Suzuki-Miyaura Reaction Mechanism

In order to succeed you must fail, so that you know what not to do the next time. 

Melchor, A Theoretical Study of Pd-Catalyzed C-C Cross-Coupling Reactions, Springer Theses, DOI 10.1007/978-3-319-01490-6 6, 

It should be noted, however, that the transmetalation reaction via the two proposed mechanisms (i.e. pathways A and B) leads to the formation of the same reaction intermediate (S-3, Fig. 6.2). Thus, assuming that this species precedes the step with 

In the following sections, a brief summary of the experimental work of Fernandez and Lassaletta [47] will be presented, followed by our theoretical results obtained on this study. The reaction mechanism is divided in three steps (i) oxidative addition, (ii) transmetalation, and (Hi) reductive elimination, each of which presented in a separated section. It has to be mentioned, however, that this study is in process of completion. Therefore, the theoretical results and conclusions presented in this chapter are the ones obtained to date. 

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Last but not least, theoretical calculations on the investigated asymmetric Suzuki-Miyaura coupling showed that the mechanism for the transmetalation step differs from the typical reaction pathway proposed in the literature. This is owing to the relative lability of the bis-hydrazone ligand, which can easy dissociate one of the N atoms directly coordinated to Pd. As far as the stereochemistry of the reaction is concerned, calculations so far do not provide an explanation for the high enantios-electivities observed in the experiments. Two possible reasons are either the true pathway for the reaction has not been identified yet, or an interconversion among... 

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