Ring Opening and C(ω)-S Coupling: Nickel-Mediated Transformation of Alicyclic Alkoxyhydroperoxides

Ozonolysis of cycloalkanone semicarbazones in alcohol containing solution with the subsequent addition of nickel (II) dithiocarbamates or xanthates was found to result in omega-xanthyl or omega-dithiocarbamyl carboxylic acid esters. The reaction proceeds in several steps. The initial one is cycloalkanone semicarbazone ozonolysis in the presence of alcohol, which leads to alicyclic alkoxyhydroperoxide. The second step is an extraordinary interaction between the alkoxyhydroperoxide and nickel (II) dithiocarbamate or xanthate, which proceeds via alkoxy radical formation and its subsequent beta-scission, resulting in C-S coupling products. The developed method allows to obtain omega-xanthyl or omega-dithiocarbamyl esters in yields up to 52 % relative to the initial cycloalkanone semicarbazone.