The hydrogenolysis of C–C bonds is one of the most important processes in the petroleum industry. These transformations typically rely on heterogeneous catalysts and take place at high temperatures and high pressures with limited selectivity. Employing homogeneous transition metal catalysts, while allowing the hydrogenolysis of C–C bonds to proceed under much milder conditions, is only suitable for substrates containing strained C–C bonds or directing groups. Here we report that a borenium complex can catalyse the selective hydrogenolysis of unstrained C(aryl)–C(alkyl) bonds of alkylarenes in the absence of directing groups at ambient temperature, affording the corresponding alkanes and arenes. Mechanistic studies suggest a reaction pathway that involves a synergistic activation of dihydrogen by the borenium complex and alkylarenes, followed by retro-Friedel–Crafts reaction to cleave the C(aryl)–C(alkyl) bonds. The synthetic utility of this protocol is demonstrated by the conversion of post-consumer polystyrene into valuable benzene and phenylalkanes with mass recovery rates above 90%.
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We thank G. Tang, L. Wang and Y. Zhao for their assistance with GC–MS, NMR and inductively coupled plass mass spectrometry experiments. Financial support for this work was provided by the National Natural Science Foundation of China (21871051 (H.W.), 21873019 (Z.H.L.) and 22071027 (H.W.)), the Shanghai Science and Technology Committee (19DZ2270100) and Fudan University.
The authors declare no competing interests.
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Xu, Y., Yang, Y., Liu, Y. et al. Boron-catalysed hydrogenolysis of unactivated C(aryl)–C(alkyl) bonds. Nat Catal 6, 16–22 (2023). https://doi.org/10.1038/s41929-022-00888-y