N,N'-disubstituted guanidine high-potency sweeteners

The role and function of the aryl group in the highly potent trisubstituted guanidine sweeteners 7a-d was investigated. Four disubstituted guanidines, lacking the aryl group, were prepared. These guanidines contain a hydrophobic substituent on one nitrogen and a carboxymethyl group substituted on one of the other nitrogens. They were found to be tasteless or to have a significantly lower sweetness potency than the corresponding trisubstituted compounds. Possible rationales for the effects of structure on the sweet taste activity are discussed.