The Use of Chemical Probes To Differentiate between Polar and SET-Hydrogen Atom Abstraction Pathways Involved in the Reduction Reaction Promoted by an 8-Al-4 Anion

Article abstract of DOI:10.1021/jo00074a014

The mechanism for the reduction of aromatic ketones and alkyl halides with lithium tetrakis(N-dihydropyridyl)aluminate was found to proceed competitively by hydride reduction and by single electron transfer (SET)-hydrogen atom abstraction processes.A series of ketyl fragmentation probes were used to differentiate the two pathways.A SET process is the dominant pathway when the ketones involved are sterically hindered or when strong electron acceptors are used as the substrates.The observation that EPR-active intermediates can be detected, or that small amounts of radical derived products are formed, demonstrates only that a SET pathway is available but cannot be used to establish the mechanism of the major product-forming reactions.