Synthesis of Unusually Substituted Ureas Starting from Bis(1,3,4‐thiadiazolo)‐1,3,5‐triazinium Halides via Oxo‐imidothioate Zwitterions

Bis(1,3,4‐thiadiazolo)‐1,3,5‐triazinium halides 1 can be converted into various products such as guanidines or bis(azolyl)alkanes. However, they also react with hydroxide ions in aqueous solution to form novel heterocyclic‐substituted ureas 2a – i . The yields were increased from moderate to good or excellent in the presence of excess guanidine 3 . The assumption that hydrogen‐bonded intermediate encounter complexes EC are formed gives a reasonable explanation for the observed reaction path. The molecular structures of some of the crystalline products 2 were determined by X‐ray analysis. Furthermore, with copper(II) a dinuclear complex 8 is formed with the two metal ions in a distorted octahedral environment; a water molecule acts as a bridging ligand between the Cu II ions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)