Method for preparing polymer maleimides
View Patent ↗Methods for preparing polymeric reagents bearing a maleimide are provided. Also provided are compositions comprising the polymeric reagents, and conjugates prepared by polymeric reagents obtained by the described methods.
1. A synthetic method comprising:
a) combining a composition comprising a plurality of amine-terminated, water-soluble polymers, each amine-terminated, water-soluble polymer in the plurality encompassed by having the structure,
POLY-(X 2 ) c —NH 2 ,
wherein
POLY is a water-soluble polymer,
(c) is zero or one, and
X 2 , when present, is a spacer moiety,
with a composition comprising a plurality of maleimide reagents, each maleimide reagent in the plurality encompassed by the structure,
wherein
Y 1 is O or S,
Y 2 is O or S,
(a) is an integer from 1 to 20,
R 1 , in each instance, is independently H or an organic radical,
R 2 , in each instance, is independently H or an organic radical,
R 3 , in each instance, is independently H or an organic radical, and
R 4 , in each instance, is independently H or an organic radical,
under substantially nonaqueous conditions to form a composition comprising a plurality of substituted maleamic acid-terminated, water-soluble polymers, each substituted maleamic acid-terminated, water-soluble polymer in the plurality encompassed by the structure,
wherein
POLY is a water-soluble polymer,
(b) is zero or one,
X 1 , wherein present, is a spacer moiety,
Y 1 is O or S,
Y 2 is O or S,
(a) is an integer from 1 to 20,
R 1 , in each instance, is independently H or an organic radical,
R 2 , in each instance, is independently H or an organic radical,
R 3 , in each instance, is independently H or an organic radical, and
R 4 , in each instance, is independently H or an organic radical;
b) isolating the substituted maleamic acid-terminated, water-soluble polymer to form a polymer composition wherein at least about 90% of all polymer species in the composition are substituted maleamic acid-terminated, water-soluble polymers;
c) forming a dissolved substituted maleamic acid-terminated, water-soluble polymer composition by dissolving substituted maleamic acid-terminated, water-soluble polymers contained within the substituted maleamic acid-terminated, water-soluble polymer composition; and
d) exposing the dissolved substituted maleamic acid-terminated, water-soluble polymer composition to elimination conditions to thereby result in a composition comprising a plurality of maleimide-terminated, water-soluble polymers, each maleimide-terminated, water-soluble polymer in the plurality encompassed by the structure,
wherein,
POLY is a water-soluble polymer,
(b) is zero or one,
X 1 , wherein present, is a spacer moiety,
R 3 , in each instance, is independently H or an organic radical, and
R 4 , in each instance, is independently H or an organic radical,
wherein the elimination conditions comprise conditions selected from the group consisting of heating, addition of a drying agent, and combinations thereof.
2. The method of claim 1 , wherein isolating the substituted maleamic acid-terminated, water-soluble polymer is effected by precipitation to form the substituted maleamic acid-terminated, water-soluble polymer composition.
3. The method of claim 2 , wherein precipitation is effected by adding an excess of an agent selected from the group consisting of isopropyl alcohol, diethyl ether, MTBE, heptane, THF, hexane, and mixtures thereof.
4. The method of claim 1 , carried out in an organic solvent.
5. The method of claim 4 , wherein the organic solvent is selected from the group consisting of halogenated aliphatic hydrocarbons, alcohols, aromatic hydrocarbons, halogenated aromatic hydrocarbons, amides, nitriles, ketones, acetates, ethers, cyclic ethers, and combinations thereof.
6. The method of claim 4 , wherein the organic solvent is selected from the group consisting of dichloromethane, chloroform, acetonitrile, toluene, methyl t-butyl ether, tetrahydrofuran, octanol, ethyl acetate, diethylcarbonate, acetone, cyclohexane and combinations thereof.
7. The method of claim 6 , wherein the organic solvent is dichloromethane or acetonitrile.
8. The method of claim 1 , wherein the step of combining the composition comprising a plurality of amine-terminated, water-soluble polymers with the composition comprising a plurality of maleimide reagents under substantially nonaqueous conditions to form the composition comprising a plurality of substituted maleamic acid-terminated, water-soluble polymers is carried out in the presence of basic catalyst.
9. The method of claim 1 , wherein the step of exposing the dissolved substituted maleamic acid-terminated, water-soluble polymer composition to elimination conditions is carried out in an organic solvent in the presence of a base.
10. The method of claim 9 , wherein the base is selected from the group consisting of sodium bicarbonate, potassium bicarbonate, sodium carbonate, or potassium carbonate.
11. The method of claim 9 , wherein the step of exposing the dissolved substituted maleamic acid-terminated, water-soluble polymer composition to elimination conditions is carried out at a temperature of 10 to 60° C.
12. The method of claim 1 , wherein the step of exposing the dissolved substituted maleamic acid-terminated, water-soluble polymer composition to elimination conditions is carried out in the presence of a non-nucleophilic amine catalyst.
13. The method of claim 12 , wherein the non-nucleophilic amine catalyst is selected from the group consisting of diisopropylethylamine, triethylamine, n-methyl morpholine, pyridine, N,N-Dimethyl-4-aminopyridine, 1,8-Diazabicyclo[5.4.0]undec-7-ene, and 1,4-diazabicyclo[2.2.2]octane.
14. The method of claim 1 , wherein the step of exposing the dissolved substituted maleamic acid-terminated, water-soluble polymer composition to elimination conditions comprises performing the step in the presence of a drying agent.
15. The method of claim 14 , wherein the drying agent is selected from the group consisting of NaHCO 3 , Na 2 CO 3 , CaCl 2 , CaSO 4 , MgSO 4 , KOH, Na 2 SO 4 , K 2 CO 3 , KHCO 3 , molecular sieves and combinations thereof.
16. The method of claim 1 , wherein the water-soluble polymer is a poly(ethylene glycol).
17. The method of claim 16 , wherein the poly(ethylene glycol) has a molecular weight of about 100 to about 100,000 Daltons.
18. The method of claim 1 , wherein the water-soluble polymer is a linear water-soluble polymer.
19. The method of claim 1 , wherein the water-soluble polymer is CH 3 O—(CH 2 CH 2 O) n —CH 2 CH 2 a is one, and further wherein n is 2 to 4000.
20. The method of claim 1 , wherein the water-soluble polymer is branched.
21. The method of claim 1 , wherein the substantially nonaqueous conditions represents a reaction medium having less than 1000 parts per million of water.
22. The method of claim 21 , wherein the substantially nonaqueous conditions represents a reaction medium having less than 100 parts per million of water.
23. The method of claim 22 , wherein the substantially nonaqueous conditions represents a reaction medium having less than 60 parts per million of water.