Reductive coupling of aliphatic cyclic imides with benzophenones by low-valent titanium

The reductive coupling of aliphatic cyclic imides with benzophenones by Zn-TiCl4 in THF gave two- and four-electron reduced products selectively by controlling the reaction conditions. Although cyclic and acyclic products were formed as mixtures in most cases, cyclic dehydrated products could be selectively obtained by heating the product mixtures in the presence of cat. p-TsOH.