A convergent route to structures with multiple contiguous carbon–nitrogen bonds. The divergent role of N-acyl groups

The radical addition of xanthates to N,N-diacetyl imidazol-2-one can be followed by a second addition to N,N-di-Boc imidazol-2-one to give after reductive dexanthylation a protected tetra-amine possessing four contiguous carbon–nitrogen bonds, or even five if the starting xanthate itself bears a protected amine. The success of this sequence hinges on the difference in radical stability between radicals substituted by an N-acyl and N-carbamoyl nitrogens, which allows control of the radical addition and prevents the formation of oligomers.