The HgCl2-promoted guanylation reaction was studied with various substituted thiourea starting materials and the scope and limitations are presented. The process was found to be effective with thioureas containing at least one N-conjugated substituent. Such activating groups include N-carbonyl-(acyl, alkoxycarbonyl, carbamoyl, etc.), N-cyano-, N-sulfonyl-, and N-aryl-substituents.
