Patent ID: 7875712

Claim:
A compound of formula Ib: wherein: between R 3 and R 4 represents a single or double bond; Z is oxygen or sulfur; R 1 is hydrogen, —CHN 2 , —R, —CH 2 OR, —CH 2 SR, or —CH 2 Y; R is a C 1-12 aliphatic, aryl, aralkyl, heterocyclyl, or heterocyclylalkyl; Y is an electronegative leaving group; R 2 is CO 2 H, CH 2 CO 2 H, or esters, amides or isosteres thereof; R 3 is hydrogen, a side chain of a natural α-amino acid, or a substituted or unsubstituted group having a molecular weight up to about 140 Daltons selected from C 1-12 aliphatic, 5-14 membered aryl, (5-14 membered aryl) -(C 1-12 -alkyl)-, 3-9 membered heterocyclyl, or (3-9 membered heterocyclyl)-(C 1-12 alkyl)-; wherein said R 3 is optionally substituted with halogen, —R, —OR, —OH, —SH, —SR, acyloxy, phenyl (Ph), —OPh, —NO 2 , —CN, —NH 2 , —NHR, —N(R) 2 , —NHCOR, —NHCONHR, —NHCON(R) 2 , —NRCOR, —NHCO 2 R, —CO 2 R, —CO 2 H, —COR, —CONHR, —CON(R) 2 , —S(O) 2 R, —SONH 2 , —S(O)R, —SO 2 NHR, —NHS(O) 2 R, ═O, ═S, ═NNHR, ═NNR 2 , ═N—OR, ═NNHCOR, ═NNHCO 2 R, ═NNHSO 2 R, or ═NR; R is C 1-6 aliphatic; Ring B is a nitrogen-containing 5-7 membered ring having 0-2 additional ring heteroatoms selected from nitrogen, oxygen or sulfur; R 5 is R 6 , (CH 2 ) n R 6 , COR 6 , CO 2 R 6 , SO 2 R 6 , CON(R 6 ) 2 , or SO 2 N(R 6 ) 2 ; n is one to three; and each R 6 is independently selected from hydrogen, an optionally substituted C 1-4 aliphatic group, an optionally substituted C 6-10 aryl group, or a mono- or bicyclic heteroaryl group having 5-10 ring atoms.