Patent ID: 8324410

Claim:
A compound having the formula: or a pharmaceutically acceptable salt thereof, wherein [N] is a weak-base moiety selected from the group consisting of N-methyl-piperazino, morpholino, pyrrolidino, piperidino, bis-piperazino and bis-piperidino; and (Spacer) is a linking group connecting the carbonyl attached to the 2′ oxygen atom and [N] wherein (Spacer) is selected from the group consisting of (i) a C 1-10 alkylene group; (ii) a C 2-10 alkylene group wherein one or more CH2 is replayed by O, NH, or S; and (iii) a C 2-10 alkylene group wherein one or more pairs of adjacent C atoms share a double bond of E- or Z-geometry, or a triple bond.