Patent ID: 7119080

Claim:
A compound having the formula (1a): or a pharmaceutically acceptable salt thereof; wherein P is hydrogen or an amino group protecting moiety; A is zero; X 2 is —C(O)—NH—; R is hydrogen or C 1-8 alkyl; R 2 is —CH 2 —R 5 ; R 3 is C 4 alkyl; R 5 is aryl or cycloalkyl, wherein R 5 is optionally substituted by one or two substituents independently selected from the group consisting of C 1-6 alkyl, C 3-8 cycloalkyl, C 1-6 alkyl(C 3-8 )cycloalkyl, C 2-8 alkenyl, C 2-8 alkynyl, cyano, amino, C 1-6 alkylamino, di(C 1-6 )alkylamino, benzylamino, dibenzylamino, nitro, carboxy, carbo(C 1-6 )alkoxy, trifluoromethyl, halogen, C 1-6 alkoxy, C 6-10 aryl, C 6-10 aryl(C 1-6 )alkyl, C 6-10 aryl(C 1-6 )alkoxy, hydroxy, C 1-6 alkylthio, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, C 6-10 arylthio, C 6-10 arylsulfinyl, C 6-10 arylsulfonyl, C 1-6 alkyl(C 6-10 )aryl, and halo(C 6-10 )aryl; Z 1 and Z 2 are each independently one of alkyl, hydroxy, alkoxy, or aryloxy, or together Z 1 and Z 2 form a moiety derived from a dihydroxy compound having at least two hydroxy groups separated by at least two connecting atoms in a chain or ring, said chain or ring comprising carbon atoms and, optionally, a heteroatom or heteroatoms which can be N, S, or O.