I've recently come across a couple examples of intramolecular alkene hydroamination accomplished by treatment with LDA followed by visible light irradiation (tungsten light bulb):[1,2]
I'd assume that this proceeds via some kind of radical mechanism, with the initially formed amide ion losing one electron to form an aminyl radical which then adds into the alkene. Trost also suggests that the addition is facilitated by an SET:
My question is – what species is taking the electron away, and how is that species generated? There doesn't seem to be any decent electron acceptor in this system, unlike, for example, Ru(II) in a photoredox mechanism. If one is aware of any mechanistic studies which have been carried out, it would be an added bonus.
- Kou, K. G. M.; Pflueger, J. J.; Kiho, T.; Morrill, L. C.; Fisher, E. L.; Clagg, K.; Lebold, T. P.; Kisunzu, J. K.; Sarpong, R. A Benzyne Insertion Approach to Hetisine-Type Diterpenoid Alkaloids: Synthesis of Cossonidine (Davisine). J. Am. Chem. Soc. 2018, 140 (26), 8105–8109. DOI: 10.1021/jacs.8b05043.
- Trost, B. M.; Tang, W. Enantioselective Synthesis of (−)-Codeine and (−)-Morphine. J. Am. Chem. Soc. 2002, 124 (49), 14542–14543. DOI: 10.1021/ja0283394.