Aspartyldipeptide derivatives and sweetener compositions containing the same

An aspartyldipeptide compound or mixture of compounds of the following formula (I) or biologically acceptable salts thereof:

• L-Asp-X-NH-C*HR.sub.1 R.sub.2 (I)
• wherein R.sub.1 represents an alkyl group having from 1 to 6 carbon atoms, or an alkoxymethyl group having from 2 to 7 carbon atoms;
• R.sub.2 represents a phenyl group, a benzyl group, a cyclohexyl group, or a cyclohexylmethyl group, the structure having the C* atom is of an (S) configuration when R.sub.1 is an alkyl group and is of an (R) configuration when R.sub.1 is an alkoxymethyl group;
• wherein when R.sub.1 is an alkyl group, X represents a residue of a D-.alpha.-amino acid or Dl-.alpha.-amino acid selected from the group consisting of D-norleucine, D-leucine, D-isoleucine, D-alloisoleucine, D-threonine, D-O-methylthreonine, D-allothreonine, D-O-methylallothreonine, and D- an DL-furylglycine, or a residue of a cyclic or acyclic .alpha.,.alpha.-dialkylamino acid having from 3 to 6 carbon atoms, but when R.sub.1 is an alkoxymethyl group, X represents a residue of a D-.alpha.-amino acid or a DL-.alpha.-amino acid 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-phenylglycine, and D-and DL-furylglycine, or a residue of a cyclic or acyclic .alpha.,.alpha.-dialkylamino acid having from 3 to 6 carbon atoms;
• and the bond between L-Asp and X is an .alpha.-bond, and wherein X is not a residue of D-norleucine or D-leucine when R.sub.1 represents an alkyl group and R.sub.2 represents a phenyl group.