Patent ID: 8653131

Claim:
A compound of Formula I: wherein Y is an activating group; X is selected from the group consisting of O, S and NR 3 ; n is 1, or 2; POLYMER is a water soluble, non-peptidic polymer wherein POLYMER does not comprise a poly(alkylene glycol); R 1 , and R 2 , are independently selected from the group consisting of hydrogen, (C 1 -C 6 )-alkyl, (C 1 -C 6 )-alkylenearyl, and aryl with the proviso that at least one of R 1 , and R 2 , is different from hydrogen; and R 3 , is selected from the group consisting of hydrogen, (C 1 -C 6 )-alkyl, (C 1 -C 6 )-alkylenearyl, and aryl.