Abstract
Alkoxyl radicals 9 (XO• ), generated by photolysis of thiocarbamates 8 , were found to initiate and undergo self-terminating radical oxygenations, in which alkynes are transformed into ketones. With this result, we have shown that every major class of organic O -centered radicals can act as O -atom synthon in this sequence, demonstrating the generality of this novel concept in radical chemistry. Theoretical investigations of the terminating homolytic scission of the O-X bond reveal that resonance stabilization in the cleaved radical X• (e.g. benzyl, allyl) both lowers the activation barrier, ΔE‡
tert -butyl) only reduces ΔE‡
• as well as the initial radical addition to the alkyne triple bond must be of similar importance.
Key words
radicals - alkynes - oxidations - photochemistry - computational chemistry
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