Heterobifunctional poly(ethylene glycol) containing acid-labile amino protecting groups and uses thereof

1. A compound of formula I:

or a salt thereof, wherein:

n is about 10 to about 40, about 40 to about 60, about 60 to about 90, about 90 to about 150, about 150 to about 200, about 200 to about 250, about 300 to about 375, about 400 to about 500, about 650 to about 750, about 5 to about 10, about 5 to about 15, 50±10, 80±10, 115 ±10, 180±10, or 225±10;

—N═R x (R y ) is:

G 1 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C 1-12 hydrocarbon chain, wherein 0-6 methylene units of the chain are independently replaced by -Cy-, or —O—;

L 2 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C 1-12 hydrocarbon chain, wherein 0-6 methylene units of the chain are independently replaced by -Cy-, —O—, —NR—, —S—, —OC(O)—, —C(O)O—, —C(O)—, —SO—, —SO 2 —, —NRSO 2 —, —SO 2 NR—, —NRC(O)—, —C(O)NR—, —OC(O)NR—, or —NRC(O)O—, wherein:

each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur;

each R is independently hydrogen or an optionally substituted aliphatic group;

R 2 is hydrogen, halogen, NO 2 , CN, N 3 , —P(O)(OR) 2 , —P(O)(X) 2 , a 9-30-membered crown ether, or an optionally substituted group selected from aliphatic, a 5-8 membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, an 8-10 membered saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or a detectable moiety; and

each X is independently halogen.

2. The compound according to claim 1 , wherein:

L 2 is -Cy-, —C(O)—, —C(O)NH—, —NH—O—, —O-Cy-CH 2 NH—O—, —NHC(O)—, —OCH 2 —, —OCH 2 C(O)—, —OCH 2 CH 2 C(O)—, —OCH 2 CH 2 O—, —OCH 2 CH 2 S—, —OCH 2 CH 2 C(O)O—, —OCH 2 CH 2 NH—, —OCH 2 CH 2 NHC(O)—, —OCH 2 CH 2 C(O)NH—, —O-Cy-, —O-Cy-NH—, —NHC(O)CH 2 CH 2 C(O)O—, —OCH 2 CH 2 NHC(O)CH 2 CH 2 C(O)O—, —O-Cy-CH 2 —, —OCH 2 CH 2 NHC(O)CH 2 OCH 2 C(O)O—, —OCH 2 CH 2 NHC(O)CH 2 OCH 2 C(O)NH—, —CH 2 C(O)NH—, —CH 2 C(O)NHNH—, —OCH 2 CH 2 NHNH—, —OC(O)CH 2 CH 2 CH 2 CH 2 —, —OCH 2 CH 2 —, —NHC(O)CH 2 CH 2 —, —NHC(O)CH 2 CH 2 CH 2 —, —OC(O)CH 2 CH 2 CH 2 —, —O-Cy-C(O)—, —O-Cy-C(O)O—, —O-Cy-C(O)O—Cy-, —O-Cy-OCH 2 CH(CH 3 )C(O)O—, —O-Cy-C(O)O—, —O-Cy-OCH(CH 3 )CH 2 C(O)O—, —OCH 2 C(O)O—, —OCH 2 C(O)NH—, —OCH 2 O—, —OCH 2 S—, —O-Cy-S—, or —OCH 2 NH—.

3. The compound according to claim 1 , wherein R 2 is an azide-containing group, an alkyne-containing group, a group comprising a terminal alkyne moiety, an aldehyde-containing group, a group comprising a terminal hydrazine moiety, a group comprising a terminal oxyamine moiety, an epoxide-containing group, or a group comprising a terminal maleimide moiety.

4. The compound according to claim 1 , wherein said compound is selected from the following formulae:

5. The compound of claim 1 , selected from those depicted in Tables A and B:

TABLE A

#

R a

R b

1

2

3

4

5

6

7

8

TABLE B

Entry

R a

R b

25