Rhodium porphyrin alkyls act as precursors of [RhII(por)] (por = porphyrinato dianion) metalloradicals, which is a key intermediate for carbon-hydrogen bond[1] and carbon-carbon single bond activation.[2] Activation of these strong bonds provides an important protocol for the functionalization of hydrocarbons in organic synthesis,[3] thus has gained much current interest. Herein, we disclose a facile alkylation method with alkyl halides to afford various alkyls-RhIII(por), including tertiary alkyl-RhIII(por): Rh(ttp)(1-adamantyl) (ttp = 5,10,15,20-tetratolylporphyrinato dianion), in moderate to high yields. Mechanistic investigations suggest a parallel SN2 via [RhI(ttp)]- with halogen atom transfer via [RhII(ttp)] metalloradical pathway.[4] ACKNOWLEDGEMENTS We thank Research Grants Council (No. 14300214) of Hong Kong SAR and the Hong Kong PhD Fellowship for financial support. REFERENCES [1] Wayland, B. B.; Ba, S.; Sherry, A. E. J. Am. Chem. Soc. 1991, 113, 5305-5311. [2] To, C. T.; Choi, K. S.; Chan, K. S. J. Am. Chem. Soc. 2012, 134, 11388-11391. [3] Shilov, A. E.; Shul'pin, G. B. Chem. Rev. 1997, 97, 2879-2932. [4] Yang, W.; Zuo, H.; Lai, W. Y.; Feng, S.; Pang, Y. S.; Hung, K. E.; Yu, C. Y.; Lau, Y. F.; Tsoi, H. Y.; Chan, K. S. Organometallics 2015, 34, 4051-4057.

Facile aerobic alkylation of rhodium porphyrins with alkyl halides

251st National Meeting (2016)

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