Patent ID: 8703941

Claim:
A compound of formula IV-i: or a pharmaceutically acceptable salt thereof, wherein: each R is independently hydrogen or an optionally substituted group selected from C 1-6 aliphatic, aryl, 4-7 membered saturated or partially unsaturated heterocyclic having 1-2 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or 5-6 membered heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or: two R groups on the same nitrogen are taken together with their intervening atoms to form a 4-7 membered saturated, partially unsaturated, or heteroaryl ring having 0-3 heteroatoms, in addition to the nitrogen, independently selected from nitrogen, oxygen, or sulfur; and L is a C 1-6 bivalent hydrocarbon chain wherein one or two methylene units of the chain are optionally and independently replaced by —NR—, —N(R)C(O)—, —C(O)N(R)—, —N(R)SO 2 —, —SO 2 N(R)—, —O—, —C(O)—, —OC(O)—, —C(O)O—, —S—, —SO— or —SO 2 —.