Patent ID: 8476306

Claim:
A compound having a structure according to the following formula, or a salt thereof, wherein P 1 is an amino acid residue formed from glycine, alanine, serine, or proline; and R 5 is selected from the group consisting of (3-pyridylmethyl)sulfonyl, (4-pyridylmethyl)sulfonyl, (2-pyridylmethyl)sulfonyl, ((3-(trifluoromethyl)phenyl)methyl)sulfonyl), ((4-(trifluoromethyl)phenyl)methyl)sulfonyl), 2-Cl-benzyl sulfonyl, 3-Cl-benzylsulfonyl, 4-Cl-benzylsulfonyl, 2-methylbenzylsulfonyl, 3-methylbenzylsulfonyl, and 4-methylbenzylsulfonyl.