Patent ID: 8623846

Claim:
A compound of the formula I: or a pharmaceutically acceptable salt thereof, wherein R 3 is hydrogen, deuterium, —OH, —OC 1-6 alkyl, or halogen; R 8 is hydrogen, deuterium, or —C 1-6 alkyl; R 11 and R 12 are independently hydrogen, —C 1-6 alkyl, —OH, —OC 1-6 alkyl, or halogen; R 13 and R 14 are independently —C 1-6 alkyl, —(CH 2 ) 1-2 OH, or —OC 1-6 alkyl, or, together with the nitrogen atom to which they are attached, form a 4- to 7-membered heterocyclic ring containing one nitrogen atom and 0 or 1 oxygen atoms, wherein said ring is unsubstituted or mono-, di- or tri-substituted with halogen or —C 1-6 alkyl; —C(O)OCH 2 CH 2 N + (CH 3 ) 3 , —C(O)NHCH(R 17 )OR 16 , or —C(O)NHCH(R 17 )C(O)NHCH(R 18 )C(O)OR 16 ; R 16 is hydrogen, —C 1-6 alkyl, or —(CH 2 ) 1-2 N + R 19 R 20 R 21 ; and R 1 , R 2 , R 4 , R 5 , R 6 , R 7 , R 9 , R 10 , R 17 , R 18 , R 19 , R 20 , and R 21 are independently hydrogen or —C 1-6 alkyl.