Patent ID: 7829561

Claim:
A compound of formula I: or a pharmaceutically acceptable salt thereof, wherein: R 1 is hydrogen, CHN 2 , R, or —CH 2 Y; R is an aliphatic group, an aryl group, an aralkyl group, a heterocyclic group, or a heterocyclylalkyl group; Y is halogen, arylsulfonyloxy, alkylsulfonyloxy, trifluoromethanesulfonyloxy, OR, SR, —OC═O(R), or —OPO(R 3 )(R 4 ); R 2 is CO 2 H, CH 2 CO 2 H, or an ester of CO 2 H or CH 2 CO 2 H selected from the group consisting of C 1-12 aliphatic esters, aryl esters, aralkyl esters, heterocyclyl esters, heteroclyclylalkyl esters; C 1-12 aliphatic amides, aryl amides, aralkyl amides, keterocyclyl amides, and heterocyclylalkyl amides; or R 2 is an isostere of CO 2 H or CH 2 CO 2 H selected from the group consisting of CONHSO 2 (alkyl) and CH 2 CONHSO 2 (alkyl); X 2 —X 1 is C(R 3 ) 2 —N, C(R 3 )═N, or C(═O)—N; each R 3 is independently selected from hydrogen or C 1-6 aliphatic, Ring C is a fused aryl ring; n is 0, 1 or 2; and each methylene carbon in Ring A is optionally and independently substituted by ═O, or by one or more halogen, C 1-4 alkyl, or C 1-4 alkoxy.