Patent ID: 8492564

Claim:
A compound of formula I: or a pharmaceutically acceptable salt thereof, wherein A is selected from C(O)Y 13 , C(O)X 13 , CH(OR A )X 13 , CH 2 Z 13 , X 2 is selected from OR 2 , O-acyl, OC(O)Z 2 , SR 2 , S-acyl, SC(O)Z 2 , NR 21 R 22 , NR 2 -acyl, and NR 2 C(O)Z 2 ; Z 2 is OR 2 , SR 2 , or NR 21 R 22 ; Y 4 is selected from OR 4 , SR 4 , and NR 23 R 24 ; X 13 is selected from C 2-7 heterocyclyl, C 6-12 aryl, C 7-14 alkaryl, C 3-10 alkheterocyclyl, and C 1-8 heteroalkyl; Y 13 is selected from OR 13 , SR 13 , and NR 25 R 26 ; Z 13 is selected from O—R 13 , O—X 13 , O-acyl, OC(O)R 13 , S—R 13 , S—X 13 , S-acyl, SC(O)R 13 , NR 25 R 26 , NR 13 -acyl, NH—X 13 , NHC(O)NH—R 13 , and NHC(O)OR 13 ; each of R 14 , R 15 , and R 16 is, independently, selected from H, halide, OR B , C 1-4 alkyl, C 2-4 alkenyl, C 2-4 alkynyl; and each of R A , R B , R 2 , R 4 , R 13 , R 21 , R 22 , R 23 , R 24 , R 25 , and R 26 is, independently, selected from H, C 1-8 alkyl, C 2-8 alkenyl, C 2-8 alkynyl, C 2-7 heterocyclyl, C 6-12 aryl, C 7-14 alkaryl, C 3-10 alkheterocyclyl, and C 1-8 heteroalkyl, or one or more of R 21 and R 22 , R 23 and R 24 , and R 25 and R 26 , combine to form a heterocyclic ring containing a nitrogen atom.