Bismuth nitrate pentahydrate: a new and environmentally benign reagent for guanidylation of N-benzoylthioureas

The bismuth nitrate-mediated guanidylation of N-benzoylthioureas was studied. This salt proved to be an effective guanylating reagent and allowed the obtention of N-benzoyl-guanidines in good yields. The methodology described is a promising alternative to the use of toxic HgCl2 in the synthesis of polysubstituted guanidines.