American Chemical Society, Journal of Organic Chemistry, 2(78), p. 658-672, 2013
DOI: 10.1021/jo302547q
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A highly efficient direct arylation process of benzylic amines with arylboronates was developed employing Ru-catalysis. The arylation takes place with greatest efficiency at the benzylic sp3 carbon. If the distance to the activating aryl ring is increased arylation is still possible but the yield drops significantly. Efficiency of the CH-activation was found to be significantly increased using 3-substituted pyridines as directing groups which can be removed after the transformation in high yield. Calculation of the energy profile of different rotamers of the substrate revealed that presence of a substituent in 3-position favors a conformation with the CH2-group adopting a position in closer proximity to the directing group and facilitating C-H insertion. This operationally simple reaction can be carried out in argon atmosphere as well as in air and under neutral reaction conditions displaying a remarkable functional group tolerance. Mechanistic studies were carried out and critically compared to mechanistic reports of related transformations.