METHODS FOR SYNTHESIS OF PERACETYLGALACTOSAMINE-1-PENTANOIC ACID
The disclosure provides methods for synthesis of peracetylgalactosamine-1-pentanoic acid, also called peracetylated D-galactosamine C5 linker or GalNAc C5 linker, using a vegetal source as a starting material, such as vegetal-sourced D-glucosamine or D-glucosamine hydrochloride. Also provided are methods for purifying the peracetylgalactosamine-1-pentanoic acid, or GalNAc C5 linker, thus produced so that the end product comprises fewer impurities.
1 . (canceled)
2 . A method of producing peracetylgalactosamine-1-pentanoic acid of Formula A
comprising using a vegetal source as a starting material.
3 . The method of claim 2 , wherein the starting material comprises D-glucosamine or D-glucosamine hydrochloride.
4 . A method for producing peracetylgalactosamine-1-pentanoic acid of Formula A
comprising:
a) subjecting D-glucosamine hydrochloride to acetylation by acetic anhydride to obtain a derivatized D-glucosamine intermediate of formula 1
b) reacting the derivatized D-glucosamine intermediate of formula 1 with trimethylsilyl trifluoromethanesulfonate (TMSOTf) to obtain a derivatized D-glucosamine intermediate of formula 2
c) subjecting the derivatized D-glucosamine intermediate of formula 2 to glycosylation by 5-hexen-1-ol to obtain a derivatized D-glucosamine intermediate of formula 3
d) subjecting the derivatized D-glucosamine intermediate of formula 3 to hydrolysis by sodium methoxide to obtain a derivatized D-glucosamine intermediate of formula 4
e) reacting the derivatized D-glucosamine intermediate of formula 4 with pivaloyl chloride to obtain a derivatized D-glucosamine intermediate of formula 5
f) reacting the derivatized D-glucosamine intermediate of formula 5 with triflic anhydride to obtain a derivatized D-galactosamine intermediate of formula 6
wherein the derivatized D-glucosamine intermediate of formula 5 is activated at O-4 position by triflate to form an intermediate O-4 triflate followed by an intramolecular attack of the intermediate O-4 triflate by the O-3-pivaloyl group resulting in an in-situ displacement of the triflate to yield the derivatized D-galactosamine intermediate of formula 6;
g) subjecting the derivatized D-galactosamine intermediate of formula 6 to hydrolysis by sodium methoxide to obtain a derivatized D-galactosamine intermediate of formula 7
h) subjecting the derivatized D-galactosamine intermediate of formula 7 to acetylation by acetic anhydride to obtain a derivatized D-galactosamine intermediate of formula 8
i) subjecting the derivatized D-galactosamine intermediate of formula 8 to oxidation by sodium periodate thereby producing the peracetylgalactosamine-1-pentanoic acid of Formula A.
5 . The method of claim 4 , wherein in step a) the acetylation of D-glucosamine hydrochloride by acetic anhydride is catalyzed by pyridine and 4-dimethylaminopyridine (DMAP).
6 . The method of claim 4 , wherein in step a) the derivatized D-glucosamine intermediate of formula 1 is extracted using ethyl acetate.
7 . The method of claim 4 , wherein in step b) the derivatized D-glucosamine intermediate of formula 2 is extracted using dichloromethane (DCM).
8 . The method of claim 4 , wherein in step c) the glycosylation of the derivatized D-glucosamine intermediate of formula 2 is performed in the presence of TMSOTf.
9 . The method of claim 4 , wherein in step d) the hydrolysis of the derivatized D-glucosamine intermediate of formula 3 is performed in methanol.
10 . The method of claim 4 , wherein in step e) the derivatized D-glucosamine intermediate of formula 4 is reacted with pivaloyl chloride in pyridine.
11 . The method of claim 4 , wherein in step e) the derivatized D-glucosamine intermediate of formula 5 is extracted using DCM and water.
12 . The method of claim 4 , wherein in step f) reacting triflic anhydride with the derivatized D-glucosamine intermediate of formula 5 is performed in the presence of pyridine and DCM.
13 . The method of claim 4 , wherein in step f) the derivatized D-galactosamine intermediate of formula 6 is extracted using ethyl acetate.
14 . The method of claim 4 , wherein in step g) the hydrolysis of the derivatized D-galactosamine intermediate of formula 6 is performed in methanol.
15 . The method of claim 4 , wherein in step h) the acetylation of the derivatized D-galactosamine intermediate of formula 7 is catalyzed by pyridine and DMAP.
16 . The method of claim 4 , wherein in step h) the derivatized D-galactosamine intermediate of formula 8 is extracted using DCM and water.
17 . The method of claim 4 , wherein in step i) the oxidation of the derivatized D-galactosamine intermediate of formula 8 is carried out in the presence of a catalyst.
18 . The method of claim 17 , wherein the catalyst is ruthenium chloride.
19 . The method of claim 4 , wherein in step i) the oxidation of the derivatized D-galactosamine intermediate of formula 8 is performed in the presence of acetonitrile, DCM, and water.
20 . The method of claim 4 , wherein in step i) the peracetylgalactosamine-1-pentanoic acid of Formula A is extracted using DCM.
21 . (canceled)
22 . The method of claim 4 , wherein the 5-hexen-1-ol used for the glycosylation of the derivatized D-glucosamine intermediate of formula 2 in step c) contains less than about 0.2% of 4-hexen-1-ol.
23 - 25 . (canceled)