Patent ID: 7399869

Claim:
A compound of Formula Ib: or stereoisomer, tautomer, or pharmaceutically acceptable salt thereof, wherein: R 1 is selected from hydrogen, methyl, isobutyl, tert-butyl, cyclohexyl, cyclopentyl, phenyl and phenyl substituted with one to three substituents selected from the group consisting on methyl, ethyl and propyl; R 2 is selected from H and C 1 -C 8 alkyl; R 3 is selected from hydrogen, methyl, isopropyl, n-propyl, isobutyl, sec-butyl, n-butyl, —CH 2 OH and —CH(OH)CH 3 , R 4 and R 5 are independently selected from H and C 1 -C 8 alkyl; each alkyl is optionally and independently substituted with one or more substituents selected from F, Cl, Br, I, OH, OR, R, ═O, ═S, ═NR, ═N + (O)(R), ═N(OR), ═N + (O)(OR), ═N-N(R) 2 , —C(═Y)R, —C(═Y)OR, —C(═Y)N(R) 2 , —N(R) 2 , —N + (R) 3 , —N(R)C(═Y)R, —N(R)C(═Y)OR, —N(R)C(═Y)N(R) 2 , —SR, —OC(═Y)R, —OC(═Y)OR, —OC(═Y)(N(R) 2 ), —OS(O) 2 (OR), —OP(═Y)(OR) 2 , —OP(OR) 2 , —P(═Y)(OR) 2 , —P(═Y)(OR)NR 2 , —S(O)R, —S(O) 2 R, —S(O) 2 NR, —S(O)(OR), —S(O) 2 (OR), —SC(═Y)R, —SC(═Y)OR, and —SC(═Y)NR 2 ; R is independently H, C 1 -C 8 alkyl, C 2 -C 8 alkenyl, C 2 -C 8 alkynyl, C 6 -C 20 aryl, C 1 -C 20 heterocyclyl, or a protecting group selected from a trialkylsilyl, a dialkylphenylsilyl, benzoate, benzyl, benzyloxymethyl, methyl, methoxymethyl, a triarylmethyl, phthalimido and tetrahydropyranyl; and Y is independently O, S, NR, N + (O)(R), N(OR), N + (O)(OR), or N-N(R) 2 .