Aspartyl dipeptide amide derivatives and sweeteners

A method of sweetening a food and/or a beverage comprising adding to a food and/or a beverage an effective amount of an aspartyl dipeptide of formula (I):

• R.sub.1 --NHC.sup.1 H(CH.sub.2 COOH)CO--X--NH--C.sup.2 R.sub.2 R.sub.3 R.sub.4 (I)
• wherein
• R.sub.1 is a hydrogen atom or a hydrocarbon group having from 1 to 13 carbon atoms;
• R.sub.2 and R.sub.3 are each, independently, an alkyl group having from 1 to 3 carbon atoms, or
• C.sup.2, R.sub.2 and R.sub.3 together form a cycloalkyl group having from 3 to 6 carbon atoms, or
• R.sub.2 is a hydrogen atom and R.sub.3 represents an alkylthioalkyl group having from 2 to 7 carbon atoms, an alkylsulfinylalkyl group having from 2 to 7 carbon atoms, an alkylsulfonylalkyl group having from 2 to 7 carbon atoms or an alkoxycarbonylmethyl group having from 2 to 7 carbon atoms;
• R.sub.4 is a phenyl group, a benzyl group, a cyclohexyl group, a cyclohexylmethyl group, a phenyl group substituted at the 2-, 3- or 4-position with a substituent selected from the group consisting of F, Cl, Br, I, a hydroxyl group, an alkoxy group having from 1 to 6 carbon atoms, a cyano group, a nitro group, an acetyl group, an amino group and an acetylamino group, a phenyl group substituted at the position 2- and 3-positions or in the 3- and 4-positions with a substituent selected from the group consisting of a methylenedioxy group, a trimethylene group and a tetramethylene group, a 2-, 3- or 4-pyridyl group, a 2- or 3-furyl group, or a 2- or 3-thienyl group;
• X is an .alpha.-amino acid residue selected from the group consisting of D-alanine, D-.alpha.-aminobutyric acid, D-norvaline, D-valine, D-norleucine, D-leucine, D-isoleucine, D-alloisoleucine, D-t-leucine, D-serine, D-O-methylserine, D-threonine, D-O-methylthreonine, D-allothreonine, D-O-methylallothreonine, D-S-methylcysteine, D-methionine, D-phenylglycine, D-furylglycine and L-furylglycine, or X is a residue of a cyclic or acyclic .alpha., .alpha.-dialkylamino acid having from 3 to 6 carbon atoms;
• the configuration at the C.sup.1 -position is (S);
• the configuration at the C.sup.2 -position is (R) or (S) when at least two of R.sub.2, R.sub.3 and R.sub.4 are different,
• or a salt thereof.