DESC:
FIELD OF THE INVENTION
The present invention describes a method for the preparation of ß-D-galactosamine and its salts and a-D-galactosamine and its salts. More specifically, this disclosure relates to synthesizing ß-D-galactosamine hydrochloride and a-D-galactosamine hydrochloride from a mixture of a/ß-D-galactosamine hydrochloride in a process efficient method.
BACKGROUND OF THE INVENTION
Carbohydrates covalently linked to other chemical constituents such as proteins and lipids on the cell surface are called as glycoconjugates. These include glycoproteins, glycolipids, peptidoglycans and lipopolysaccharides. D-galactosamine which is a naturally occurring sugar present on the cell surface, is involved in many receptors mediated signaling processes and plays structural and functional roles in various biological recognition processes, including, bacterial & viral infections, inflammatory responses, cancer metastasis, innate & adaptive immunity. The first step in many of these processes is often mediated by protein-carbohydrate interactions. Elucidation of the molecular basis of these interactions would lead to the development of carbohydrate-based therapeutics. Moreover, D-galactosamine has been used in the drug delivery system in a specific manner to the targeted cells. For example, D-galactosamine was used in vivo for the efficient delivery of the iRNA agents to the cells. Very recently, the U.S. Food and Drug Administration (FDA) approved two drugs Lumasiran and Givosiran where D-galactosamine is a key component. Hence, there is a growing interest towards the preparation of D-galactosamine. D-galactosamine obtained from the natural sources is very low in occurrence and isolation of milligram quantities requires enormous efforts. Alternatively, chemical synthesis provides a robust method for making D-galactosamine. Realizing the need for preparing D-galactosamine in an industrial scale, the present inventors have developed a simple and expedient procedure for the preparation of D-galactosamine.
Chaplin et al (J. Chem. Soc. Perkin Trans. I 1992, 235-237) reported the synthesis of peracetylated GalNAc (fully acetylated D-galactosamine) by an enzymatic process in six steps. First, free sugar N-acetyl D-glucosamine was converted to peracetyated D-GlcNAc. Then selective deprotection of acetyl group at C-6 position followed by acetyl migration from C-4 to C-6 by acid treatment generate the C-4 hydroxy derivative. Triflation of C-4 hydroxy group followed by SN2 inversion with CsOAc gave the desired peracetylated GalNAc (fully acetyl protected D-galactosamine). The disadvantageous in this method are more number of steps and the use of expensive CsOAc and biocatalyst. In addition, the authors have reported only the preparation of mixture of a/ß-galactosamine hydrochloride but they did not report the preparation of either pure ß-D-galactosamine hydrochloride or pure a-D-galactosamine hydrochloride.
Wrodnigg et al. (J. Carbohydr. Chem, 2006, 25, 33-41) reported the synthesis of N-protected galactosamine from D-tagatose in four steps with overall yield up to 25%. As per their publication, D-tagatose was converted to mixture of a/ß-N-benzyl galactosamine along with the unreacted starting material and side products via Heyns rearrangement. The next step debenzylation was done using Pd(OH)2/C under hydrogen atmosphere to get mixture of a/ß-D-galactosamine hydrochloride and unreacted starting material. In this process the disadvantageous are, the use of expensive D-tagatose as the starting material and expensive Pd(OH)2/C along with explosive and flammable hydrogen gas. In addition, the authors did not report the preparation of either pure ß-D-galactosamine hydrochloride or pure a-D-galactosamine hydrochloride. In addition, the reactions did not go for completion and there was unreacted starting material presented in both two steps along with the product.
Ling et al. (Carbohydr Res., 2010, 345, 2450–2457) describes the synthesis of 2-acetamindo-2-deoxy-1,4,6-tri-O-pivaloyl-D-galactopyranose (pivaloyl protected D-galactosamine) from N-acetyl D-glucosamine (D-GlcNAc) in three steps. The first step pivaloylation of D-GlcNAc gave C-4 hydroxy 2-acetamido-2-deoxy-1,3,6-tri-O-pivaloyl-D-galactose. In the second step, the crude product thus obtained after the work-up was directly taken for triflation of C-4 hydroxy group. In the third step, water was added directly to the reaction mass and heated the reaction mass to 60 °C for 16 h resulting C-4 triflate inversion followed pivaloyl migration from C-3 to C-4 to get 2-acetamindo-2-deoxy-1,4,6-tri-O-pivaloyl-D-galactopyranose in 58.4% overall yield, after the recrystallization. Although the authors reported the synthesis of 2-acetamindo-2-deoxy-1,4,6-tri-O-pivaloyl-D-galactopyranose(pivaloyl protected galactosamine) from starting material, D-GlcNAc, but the authors did not report further the deprotection pivaloyl protecting groups to get either ß-D-galactosamine and its salts or a-D-galactosamine and its salts (free sugars).
Hence it can be observed that there is a genuine need for synthesizing pure ß-D-galactosamine and its salts or a-D-galactosamine and its salts in higher yields and of high purity at low cost, which are commercial requirements in an industrial scalable process so that the process can be used directly for the larger scale production. The present inventors have surprisingly developed an efficient process which ameliorates the aforesaid shortcomings of the prior art.
OBJECTS OF THE INVENTION
It is an object of the present invention to overcome the drawbacks of the prior arts.
It is another object of the present invention to provide a process for the preparation of ß-D-galactosamine and its salts.
It is another object of the present invention to provide a process for the preparation of a-D-galactosamine and its salts.
It is another object of the present invention to provide a process for the preparation of a mixture of a/ß-D-galactosamine and its salts.
It is another object of present invention to provide a process for the preparation of D-galactosamine and its salts which reduces process steps, does not involve hazardous reactant conditions or use of expensive starting reagents, significantly reduces process cycle time which in turn reduces the cost, results in compounds of higher yields and of high purity, is industrially scalable, environmentally friendly, safe and very cost effective.
It is another object of present invention to provide pure ß-D-galactosamine and its salts and pure a-D-galactosamine and its salts.
SUMMARY OF THE INVENTION
According to an aspect of the present invention there is provided a process for the preparation of ß-D-galactosamine and its salts (Compounds of Formula I).

According to another aspect of the present invention there is provided a process for the preparation of a-D-galactosamine and its salts (Compounds of Formula II).

According to yet another aspect of the present invention there is provided a process for the preparation of a mixture of a/ß-D-galactosamine and its salts (Compounds of Formula III) from Compounds of Formula IV.


According to yet another aspect of the present invention there is provided pure ß-D-galactosamine and its salts (Compounds of Formula I) and pure a-D-galactosamine and its salts (Compounds of Formula II).
BRIEF DESCRIPTION OF THE DRAWING
Example embodiments are illustrated by way of example not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:
FIG.1 shows the instant method of synthesizing ß-D-galactosamine and its salts (Compounds of Formula I) and FIG.2 shows the instant method of synthesizing a-D-galactosamine and its salts (Compounds of Formula II), apparent from the corresponding drawings and from the detailed description that follows.
DETAILED DESCRIPTION OF THE INVENTION
The following description is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.
Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the scope of the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, steps or components but does not preclude the presence or addition of one or more other features, steps, components or groups thereof.
The present invention relates to the synthesis of ß-D-galactosamine and its salts (Compounds of Formula I) and a-D-galactosamine and its salts (Compounds of Formula II) using the starting reactant of Compounds of Formula IV. More specifically, the synthesis of ß-D-galactosamine and its salts (Compounds of Formula I) and a-D-galactosamine and its salts (Compounds of Formula II) using the starting Compounds of Formula IV is performed in only two steps to obtain purer compounds in less time and low cost. The instant synthesis of making ß-D-galactosamine and its salts (Compounds of Formula I) and a-D-galactosamine and its salts (Compounds of Formula II) is also less toxic, safe and cost effective.
The present disclosure also relates to a process for the preparation of a mixture of a/ß-D-galactosamine and its salts (Compounds of Formula III) and how ß-D-galactosamine and its salts (Compounds of Formula I) and a-D-galactosamine and its salts (Compounds of Formula II) are made.
The present disclosure relates to Compounds of Formula III

wherein, R1 is individually selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate, citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof,
The present disclosure further relates to a process of obtaining Compounds of Formula III from Compounds of Formula IV

wherein, R1 is individually selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof, said process comprising reacting Compounds of Formula IV with acid to obtain the Compounds of Formula III

wherein, R2 is selected from a group comprising pivaloyl, benzoyl, acetyl, trichloroacetyl, chloromethylacetyl, benzene 1,2-dicarbonyl, wherein, each of them may be optionally substituted, R3 is individually selected from a group comprising pivaloyl, benzoyl, acetyl, trichloroacetyl, chloromethylacetyl, wherein, each of them may be optionally substituted.
In an embodiment of the present disclosure, the acid is from a group comprising hydrochloric acid, hydrobromic acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid and tartaric acid, or any combination thereof. Yet in another embodiment of the present disclosure, the above process is carried out with hydrochloric acid with normality ranging from 1-11, preferably, 3-5 normality and the reaction volumes ranging from 1 - 100 volumes, preferably, 3– 10 volumes. The time period ranging from 30 minutes to 72 hours, preferably about 60 minutes to 16 hours.
The present inventors have also tried the deprotection of the protecting groups in Formula IV, under basic conditions. The deprotection was tried in various conditions, viz., using potassium carbonate in methanol, sodium methoxide in methanol, potassium hydroxide in methanol, potassium hydroxide in water/methanol, lithium hydroxide in water, sodium hydroxide in water/methanol, barium acetate in water, trimethylamine in methanol. However, it was observed that in all these reaction conditions, the product, Compounds of Formula III is isolated but in lower yields.
Yet in another embodiment of the present disclosure, the above process further comprises isolation of Compounds of Formula III, and wherein, the isolation is carried out by acts selected from a group comprising evaporation, quenching, filtration and extraction or any combination of acts in any order thereof, preferably by evaporation.
The present disclosure relates to Compounds of Formula I

wherein, R1 is selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate, citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof,
and Compounds of Formula II

wherein, R1 is selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate, citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof,
The present disclosure further relates to a process of obtaining Compounds of Formula I

and Compounds of Formula II

wherein, R1 is selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate, citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof, each of them may be optionally substituted, or salts thereof, said process comprising dissolving, evaporation and stirring of Compounds of Formula III with a solvent to obtain the compound of Formula I and dissolving of Compounds of Formula III in a suitable solvent followed by evaporation to obtain Compounds of Formula II.

wherein, R1 is selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate, citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof,
In an embodiment of the present disclosure, the solvent is from a group comprising methanol, acetone, toluene, benzene, acetonitrile, ethanol, isopropanol, tert-butanol, n-butanol, 2-butanol, isoamyl alcohol, tetrahydrofuran, 2-methyl tetrahydrofuran, ethyl acetate, n-hexane, n-heptane, methyl tertiary butyl ether, dichloromethane, chloroform, carbon tetrachloride, chlorobenzene, cyclohexane, 1,2-dichloroethane, diethylene glycol, diethyl ether, diglyme, dimethyl formamide, dimethyl sulfoxide, 1,4-dioxane, ethylene glycol, glycerin, acetic acid and aqueous hydrochloric acid, etc. or any combination thereof and the likes. In another embodiment of the present disclosure, the above process is carried out with methanol and water with volumes 1 -100, preferably, 1-10 volumes and a time period ranging from 30 minutes to 72 hours, preferably about 60 minutes to 16 hours.
Yet another embodiment of the present disclosure, the above process further comprises isolation of Compounds of Formula I and Compounds of Formula II, and wherein, the isolation is carried out by methods selected from a group comprising filtration, evaporation, quenching and extraction or any combination of acts in any order thereof, preferably by filtration or evaporation.
In brief, the preparation of Compounds of Formula I & Compounds of Formula II using Compounds of Formula IV is represented in the below schemes (1) & (2).
Scheme 1: Preparation of compounds of Formula I

Scheme 2: Preparation of compounds of Formula II
The present invention also relates to the preparation of a mixture of a/ß-D-galactosamine and its salts (Compounds of Formula III) from Compounds of Formula IV as shown in below Scheme 3:

Scheme 3: Preparation of compounds of Formula III
In brief, Compounds of Formula I & Compounds of Formula II are obtained from Compounds of Formula IV in two steps.


Scheme 4
In an embodiment, there is provided a process for preparing ß-D-galactosamine and its salts (Compounds of Formula I) and a-D-galactosamine and its salts (Compounds of Formula II), said process comprising steps of:
step a) reacting Compounds of Formula IV with acid to obtain Compounds of Formula III

wherein, R1 is selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate, citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof,
step b) dissolving Compounds of Formula III with a mixture of solvents followed by evaporation and stirring the reaction mass with a mixture of solvents followed by filtration to obtain the product Compounds of Formula I

wherein, R1 is selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate, citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof,
or step c) dissolving Compounds of Formula III in a suitable solvent followed by evaporation to obtain Compounds of Formula II.

wherein, R1 is selected from a group comprising hydrogen chloride, hydrogen bromide, hydrogen sulphate, hydrogen phosphate, nitrate, perchlorate, trifluoroacetate, trichloroacetate, citrate and tartarate salts, wherein, each of them may be optionally substituted, or salts thereof,
In an embodiment of the present disclosure, the salts R1, as mentioned above are selected from a group comprising hydrochloric acid, hydrobromic acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid and tartaric acid or any combination thereof. In another embodiment of the present disclosure, the above process is carried out with hydrochloric acid with normality ranging from 1-11, preferably, 3-5 normality. And the volumes of the reaction mixture are ranging from 1 – 100, preferably, 3 – 10 volumes.
In an embodiment of the present disclosure, the acid is selected from a group comprising hydrochloric acid, hydrobromic acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid and tartaric acid or any combination of mixture thereof; the solvent is selected from a group comprising methanol, water, acetone, toluene, benzene, acetonitrile, ethanol, isopropanol, tert-butanol, n-butanol, 2-butanol, isoamyl alcohol, tetrahydrofuran, 2-methyl tetrahydrofuran, ethyl acetate, n-hexane, n-heptane, methyl tertiary butyl ether, dichloromethane, chloroform, carbon tetrachloride, chlorobenzene, cyclohexane, 1,2-dichloroethane, diethylene glycol, diethyl ether, diglyme, dimethyl formamide, dimethyl sulfoxide, 1,4-dioxane, ethylene glycol, glycerin, acetic acid and aqueous hydrochloric acid, etc. or any combination thereof and the likes,
In an embodiment of the present disclosure, the above process at step (b) is carried out with methanol alone, or methanol and water or methanol and hydrochloric acid with volumes 1 -100, preferably, 1-10 volumes and a time period ranging from 30 minutes to 72 hours, preferably about 60 minutes to 16 hours.
In an embodiment, the above process at step (c) is carried out using water as solvent.
In another embodiment of the present disclosure, the above process is carried out at a temperature ranging from 0°C to 150 °C, preferably about 10 – 30 °C and for a long period ranging from about 30 minutes to about 72 hours, preferably about 30 minutes to 20 hours.
In another embodiment of the present disclosure, the above process steps (a) (b) and (c) further comprise steps of precipitation or evaporation or isolation or a combination thereof of the corresponding compound obtained, and wherein, the isolation is carried out by methods selected from a group comprising filtration, evaporation and extraction or any combination of methods in any order thereof.
The present disclosure further relates to use of Compounds of Formula III, thereof for preparation of ß-D-galactosamine and its salts (Compounds of Formula I) & a-D-galactosamine and its salts (Compounds of Formula II).
In an object of the present disclosure, Compounds of Formula I & Compounds of Formula II, thereof are provided wherein, said compounds are employed in various applications. Further, the Compounds of Formula I & Compounds of Formula II serve as industrially useful starting compounds for the efficient synthesis of pharmaceutically significant drug compounds or drug carriers to the specific targeted cells.
In an exemplary embodiment of the present disclosure, the Compounds of Formula I and Compounds of Formula II are employed for the synthesis of pharmaceutically significant drug compounds or drug carriers to the specific targeted cells. In particular, the synthetic procedures for the preparation of ß-D-galactosamine and its salts (Compounds of Formula I) and a-D-galactosamine and its salts (Compounds of Formula II) involve Compounds of Formula III as intermediate. Further the process for the preparation of ß-D-galactosamine and its salts (Compounds of Formula I) and a-D-galactosamine and its salts (Compounds of Formula II) described in the present disclosure are cost-effective, scalable and efficient.
In an embodiment of the present disclosure, the various chemical compounds and intermediates as disclosed therein are as follows:

wherein, R1 is individually selected from a group comprising but not limited to hydrochloric acid, hydrobromic acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid and tartaric acid or any combination thereof, wherein, each of them may be optionally substituted, or salts thereof,

wherein, R1 is individually selected from a group comprising but not limited to hydrochloric acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid and tartaric acid or any combination thereof, wherein, each of them may be optionally substituted, or salts thereof,

wherein, R1 is individually selected from a group comprising but not limited to hydrochloric acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid and tartaric acid or any combination thereof, wherein, each of them may be optionally substituted, or salts thereof,
Method of synthesizing; Step 1:

Compounds of Formula III are prepared by the treatment of Compounds of Formula IV, with a suitable acid in the presence of suitable solvent at a temperature of about -10 °C to about 150 °C for a time period ranging from about 30 minutes to 72 hours. Preferably, the reaction is carried out at a temperature of about 30 °C. to 100 °C. and preferably for a time period of 30 min to 16 h.
In an embodiment of the present disclosure, suitable acid is selected from hydrochloric acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid and tartaric acid, etc. or any combination thereof. In an embodiment, suitable acid is hydrochloric acid and the normality of the hydrochloric acid ranging from 1-11 normality, preferably 3-5 normality. Further suitable volumes of hydrochloric acid for the reaction is 1 -100 volumes, preferably 3-10 volumes.
Method of synthesizing; Step 2:
The Compounds of Formula I is directly synthesized by dissolving, evaporating and stirring of Compounds of Formula III with a suitable solvent at a temperature of about -20 °C. to 100 °C. for a time period ranging from about 60 minutes to 72 hours. The stirring is preferably carried out at a temperature of about 10 °C. to 30 °C. and a time period of about 1 - 36 hours.

In an embodiment, the mixture of a/ß-D-galactosamine and its salts (Compound of Formula III) is dissolved by stirring in an alcohol solvent optionally in combination with other non-alcohol solvents; and optionally heating the reaction mixture.
In an embodiment, the alcohol solvent is selected from methanol, ethanol, isopropanol, tert-butanol, n-butanol, 2-butanol, isoamyl alcohol, or combinations thereof.
In an embodiment, the non-alcohol solvent is selected from water, acetone, toluene, benzene, acetonitrile, tetrahydrofuran, 2-methyl tetrahydrofuran, ethyl acetate, n-hexane, n-heptane, methyl tertiary butyl ether, dichloromethane, chloroform, carbon tetrachloride, chlorobenzene, cyclohexane, 1,2-dichloroethane, diethylene glycol, diethyl ether, diglyme, dimethyl formamide, dimethyl sulfoxide, 1,4-dioxane, ethylene glycol, glycerin, acetic acid, aqueous hydrochloric acid or combinations thereof.
In an embodiment, the ratio of alcohol solvent to non-alcohol solvent at step ranges from 100:1 to 10:1.
In an embodiment, the above process is carried out with methanol alone, or combination of methanol and water or combination of methanol and hydrochloric acid.
In another embodiment, after stirring for a specific time, Compounds of Formula I is isolated by suitable technique such as filtration, extraction and quenching, preferably by filtration. In an embodiment, Methanol and water are used as solvents for dissolving and stirring.
Method of synthesizing; Step 3:
The Compounds of Formula II are directly synthesized by dissolving Compounds of Formula III in a suitable solvent, followed by evaporating at a temperature of about 40 °C. to 100 °C. for a time period ranging from about 60 minutes to 72 hours. The evaporation is preferably carried out at a temperature of about 50 °C. to 80 °C.

In an embodiment of the present disclosure, suitable solvent is selected from water.
In another embodiment, after stirring Compounds of Formula III with water for a specific time, Compounds of Formula II is isolated by suitable technique such as evaporation, filtration, extraction and quenching, preferably by evaporation. Water is used as solvent for dissolving.
EXAMPLES
The following examples are meant to illustrate the present invention. The examples are presented to exemplify the invention and are not to be considered as limiting the scope of the invention.
Example 1
Preparation of a mixture of a/ß-D-galactosamine hydrochloride (Compound of Formula III):
Method 1:

2-Acetamido-2-deoxy-1,4,6-tri-O-pivaloyl-ß-D-galactopyranose (Compound of Formula IV, about 100 g) is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Then, 3N hydrochloric acid (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. over a period of 5 - 10 minutes. The resulting reaction mixture is allowed to stir at a temperature ranging about 90 - 100 °C. over a period of about 4 - 6 hours. Completion of the reaction is monitored by thin layer chromatography (TLC). Thereafter, the reaction mixture is transferred into a single neck round bottom flask and concentrated to dryness under reduced pressure using a rotary evaporator to remove aqueous hydrochloric acid. The product, mixture of a/ß-D-galactosamine hydrochloride [Compound of Formula III] (about 43.0 g, 95%) obtained is taken to next step. The obtained product contains a/ß-mixture is in a range of 20 – 90% of a-isomer & 10 – 70% of ß-isomer. 1H NMR (CD3OD, 400 MHz): 5.34 – 5.32 (d, J = 4.0 Hz, 1H, H-1a), 4.70 – 4.68 (d, J = 8.8 Hz, 1H, H-1ß), 4.09 – 4.12 (m, 1H), 3.98 – 3.91 (m, 2H), 3.72 – 3.63 (m, 3H), 3.36 – 3.32 (m, 1H), 3.09 – 3.01 (m, 1H). LC-MS (ESI): 180 [(M+H)+]
Preparation of a mixture of a/ß-D-galactosamine hydrochloride (Compound of Formula III):

Method 2:

2-Acetamido-2-deoxy-1,4,6-tri-O-pivaloyl-ß-D-galactopyranose (Compound of Formula IV, about 100 g) is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Then, 10% sulphuric acid (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. over a period of 5 - 10 minutes. The resulting reaction mixture is allowed to stir at a temperature ranging about 90 - 100 °C. over a period of about 4 - 6 hours. Completion of the reaction is monitored by thin layer chromatography (TLC). Thereafter, the reaction mixture is transferred into a single neck round bottom flask and concentrated to dryness under reduced pressure using a rotary evaporator to remove aqueous hydrochloric acid. The product, mixture of a/ß-D-galactosamine hydrochloride [Compound of Formula III] (about 43.0 g, 95%) obtained is taken to next step. The obtained product contains a/ß-mixture is in a range of 20 – 90% of a-isomer & 10 – 70% of ß-isomer.
Preparation of a mixture of a/ß-D-galactosamine:
Method 3: (Comparative Example)

2-Acetamido-2-deoxy-1,4,6-tri-O-pivaloyl-ß-D-galactopyranose (Compound of Formula IV, about 100 g) is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Then, methanol (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. followed by sodium methoxide (cat.) over a period of 5 - 10 minutes. The resulting reaction mixture is allowed to stir at a temperature ranging about 40 - 60 °C. over a period of about 4 - 6 hours. Completion of the reaction is monitored by thin layer chromatography (TLC). Thereafter, acidic resin was added and filtered the reaction mixture through celite bed. Concentration of solvent under reduced pressure using a rotary evaporator resulted the product, mixture of a/ß-D-galactosamine (about 22.0 g, 47%). The obtained product contains a/ß-mixture is in a range of 20 – 90% of a-isomer & 10 – 70% of ß-isomer.
From the aforesaid, it is observed that the deprotection of the protecting groups in Formula IV, under basic conditions results in lower yields of Compounds of Formula III.
Example 2
Preparation of ß-D-galactosamine hydrochloride (Compound of Formula I):
Method 1:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Methanol (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is allowed to stir at a temperature ranging about 25-30 °C. over a period of about 16 hours. Thereafter, the precipitated product is filtered and dried under vacuum (for about 2 hours) to obtain the product, ß-D-galactosamine hydrochloride (Compound of Formula I, about 85 g, 85% in yield) as a white solid. The obtained product contains about 10 - 15% of a-isomer. 1H NMR (CD3OD, 400 MHz): 4.68 (d, J = 8.3 Hz, 1H,H-1ß), 3.86 – 3.85 (m, 1H), 3.79 – 3.71 (m, 2H), 3.68 – 3.64 (m, 1H), 3.57 – 3.54 (m, 1H), 3.09 – 3.03 (m, 1H). LC-MS (ESI): 180 [(M+H)+] HPLC Purity: 99.8%
To improve further the formation of ß-isomer and minimizing the a-isomer, Method 1 is further modified as per the below:
Method 2:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Water (about 100 mL, 1V) and methanol (1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C over a period of 10 minutes. The resulting reaction mixture is heated to 75 °C for about 30 min. The reaction mixture became clear solution. Then the solvents water and methanol are evaporated using a rotovap under reduced pressure. This operation is repeated twice. Then, the resultant product is slurried with methanol (1000 mL, 10 V) for about 4 hours. The product is filtered and dried under vacuum (for about 2 hours) to obtain, ß-D-galactosamine hydrochloride (Compound of Formula I, about 85 g, 85% in yield) as a white solid. The obtained product contains about 5 - 10% of a-isomer.

Method 3:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Water (about 100 mL, 1 V) and methanol (1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is heated to 75 °C for about 30 min. The reaction mixture became clear solution. Then the solvents water and methanol are evaporated using a rotovap under reduced pressure. This operation is repeated twice. Then the resultant product is slurried with methanol (1000 mL, 10 V) and water (10 mL, 0.1 V) for about 4 hours. The precipitated product is filtered and dried under vacuum (for about 2 hours) to obtain the product, ß-D-galactosamine hydrochloride (compound of Formula I, about 75 g, 75% in yield) as a white solid. In this case also the obtained product contains about 5% of a-isomer.
Method 4:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. 1.5 N hydrochloric acid (about 100 mL, 1 V) and methanol (1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is heated to 75 °C for about 30 min. The reaction mixture became clear solution. Then the solvents hydrochloric acid and methanol are evaporated using a rotovap under reduced pressure. The obtained product is dried under vacuum (for about 2 hours) to get, ß-D-galactosamine hydrochloride (Compound of Formula I, about 80 g, 80% in yield) as a white solid. The obtained product contains about 10 - 15% of a-isomer.
Method 5:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. 1.5 N hydrochloric acid (about 100 mL, 1 V) and methanol (1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is heated to 75 °C for about 30 min. The reaction mixture became clear solution. Then the solvents hydrochloric acid and methanol are evaporated using a rotovap under reduced pressure. Then the resultant crude material is slurried with methanol (1000 mL, 10 V) for about 4 hours. The precipitated product is filtered and dried under vacuum (for about 2 hours) to obtain the product, ß-D-galactosamine hydrochloride (Compound of Formula I, about 85 g, 85% in yield) as a white solid. The obtained product contains about 5% of a-isomer.
Method 6:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. 1.5 N hydrochloric acid (about 100 mL, 1 V) and methanol (1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is heated to 75 °C for about 30 min. The reaction mixture became clear solution. Then the solvents hydrochloric acid and methanol are evaporated using a rotovap under reduced pressure. Then the resultant product is slurried with methanol (1000 mL, 10 V) and water (5 mL, 0.05 V) for about 4 hours. The precipitated product is filtered and dried under vacuum (for about 2 hours) to obtain the product, ß-D-galactosamine hydrochloride (Compound of Formula I, about 95g, 95% in yield) as a white solid. The obtained product contains about <5% of a-isomer.
Method 7:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. 1.5 N hydrochloric acid (about 100 mL, 1 V) and ethanol (1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is heated to 75 °C for about 30 min. The reaction mixture became clear solution. Then the solvents hydrochloric acid and ethanol are evaporated using a rotovap under reduced pressure. Then the resultant product is slurried with ethanol (1000 mL, 10 V) and water (5 mL, 0.05 V) for about 4 hours. The precipitated product is filtered and dried under vacuum (for about 2 hours) to obtain the product, ß-D-galactosamine hydrochloride (Compound of Formula I, about 95g, 95% in yield) as a white solid. The obtained product contains about <5% of a-isomer.
Method 8:(Comparative example)

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Ethyl acetate (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is allowed to stir at a temperature ranging about 25-30 °C. over a period of about 16 hours. Thereafter, the precipitated product is filtered and dried under vacuum (for about 2 hours) to obtain the product, ß-D-galactosamine hydrochloride (Compound of Formula I, about 80 g, 80% in yield) as a white solid. The obtained product contains about 15 - 20% of a-isomer.
From the aforesaid example, it is observed that by using non-alcoholic solvents such as ethyl acetate, the percentage of pure ß-D-galactosamine obtained is less when compared to using alcoholic solvent such as methanol according to present invention.
Preparation of ß-D-galactosamine hydrochloride (Compound of Formula I), Scalable Process:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 500 g, obtained by following the reported procedure in Example 1), is charged to a glass line reactor equipped with a mechanical stirrer at a temperature of about 25-30 °C. 1.5 N hydrochloric acid (about 500mL, 1 V) and methanol (5 L, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is heated to 75 °C for about 30 min. The reaction mixture became clear solution. Then the solvents hydrochloric acid and methanol are evaporated under reduced pressure. Then the resultant crude material is slurried with methanol (5 L, 10 V) and water (25 mL, 0.05 V) for about 4 hours. The precipitated product is filtered and dried under vacuum (for about 2 hours) to obtain the product, ß-D-galactosamine hydrochloride (Compound of Formula I, about 475 g, 95% in yield) as a white solid. The obtained product contains about <5% of a-isomer.
Example 3
Preparation of a-D-galactosamine hydrochloride (Compound of Formula II):
Method 1:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g, obtained from the Example 1), is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Water (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is allowed to stir at a temperature ranging about 25-30 °C. over a period of about 4 hours. Thereafter, the solvent is evaporated using a rotovap under reduced pressure to get the desired product. The obtained product further dried under vacuum (for about 2 hours) to obtain the product, a-D-galactosamine hydrochloride (Compound of Formula II, about 95 g, 95% in yield) as a white solid. The obtained product contains about 10 - 15% of ß-isomer.1H NMR (CD3OD, 400 MHz): 5.33 (d, J = 4.0 Hz, 1H, H-1a), 4.06 – 4.03 (m, 1H), 3.96 – 3.91 (m, 2H), 3.75 – 3.71 (m, 2H), 3.36- 3.33 (m, 1H).
To improve further the formation of a-isomer and minimizing the ß-isomer, Method 1 is further modified as per the below:
Method 2:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g), obtained from the Example 1, is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Water (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is allowed to stir at a temperature ranging about 25-30 °C. over a period of about 10 hours. Thereafter, the solvent is evaporated using a rotovap under reduced pressure to get the desired product. The obtained product further dried under vacuum (for about 2 hours) to get, a-D-galactosamine hydrochloride (Compound of Formula II, about 95 g, 95% in yield) as a white solid. The obtained product contains about 5 - 10% of ß-isomer.
Method 3:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g), obtained from the Example 1, is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Water (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is allowed to stir at a temperature ranging about 25-30 °C. over a period of about 20 hours. Thereafter, the solvent is evaporated using a rotovap under reduced pressure to get the desired product. The obtained product further dried under vacuum (for about 2 hours) to obtain the product, a -D-galactosamine hydrochloride (compound of Formula II, about 95 g, 95% in yield) as a white solid. The obtained product contains about <5% of ß-isomer.
Method 4:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 100 g), obtained from the Example 1, is charged to a 2-necked round bottom flask equipped with a mechanical stirrer at a temperature of about 25-30 °C. Water (about 1000 mL, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is allowed to stir at a temperature ranging about 25-30 °C. over a period of about 4 hours. Thereafter, the solvent is evaporated using a rotovap under reduced pressure to get the desired product. Water (100 mL, 1V) is added and stirred for 10 minutes at room temperature. Then the solvent, water is evaporated using a rotovap. This operation is repeated one more time. The obtained product is further dried under vacuum (for about 2 hours) to get a-D-galactosamine hydrochloride (Compound of Formula II, about 95 g, 95% in yield) as a white solid. The obtained product, a-D-galactosamine hydrochloride (compound of Formula II) contains about <1% of ß-isomer.
Preparation of a-D-galactosamine hydrochloride (Compound of Formula II), Scalable Process:

a/ß-D-galactosamine hydrochloride (Compound of Formula III, about 500 g), obtained from the Example 1, is charged to a glass line reactor equipped with a mechanical stirrer at a temperature of about 25-30 °C. Water (about 5L, 10 V) is thereafter charged at a temperature ranging about 25-30 °C. The resulting reaction mixture is allowed to stir at a temperature ranging about 25-30 °C. over a period of about 4 hours. Thereafter, the solvent is evaporated to get the desired product. Water (500 mL, 1V) is added and stirred for 10 minutes at room temperature. Then the solvent, water is evaporated. This operation is repeated one more time. The obtained product is further dried under vacuum (for about 2 hours) to get a-D-galactosamine hydrochloride (Compound of Formula II, about 475 g, 95% in yield) as a white solid. The obtained product, a-D-galactosamine hydrochloride (compound of Formula II) contains about <1% of ß-isomer.
Results and Discussion: The ß-D-galactosamine and its salts (Compounds of Formula I) and a-D-galactosamine and its salts (Compounds of Formula II) described herein are synthesized as shown in FIG.1 and FIG.2, respectively. The mixture of a/ß-D-galactosamine and its salts (Compounds of Formula III) are conveniently synthesized from Compounds of Formula IV by acid treatment. The present inventors have designed the process in such a way that the Compounds of Formula III are obtained as a result of two simultaneous reactions. [1. Deprotection of protecting groups at C-1, C-4 and C-6 positions; 2. Deprotection of protecting group on the nitrogen, at C-2 position] in one-pot. Further, alcohol slurry of Compounds of Formula III would result in formation of Compounds of Formula I and water slurry of Compounds of Formula III would result in formation of Compounds of Formula II.
In an embodiment, the reaction of Compounds of Formula IV with 3N hydrochloric acid at about 90 - 100 °C smoothly yielded Compounds of Formula III with excellent yield (about 90%). Formation of Compounds of Formula III was further confirmed by its 1H NMR and LC-MS data. Then methanol and water slurry of Compounds of Formula III smoothly yielded the required Compounds of Formula I and water slurry of Compounds of Formula III resulted in formation of Compounds of Formula II with excellent yields (about 95%). Formation of Compounds of Formula I and Compounds of Formula II was further confirmed by its 1H NMR and LC-MS data.
Industrial Applicability:
The synthesis of ß-D-galactosamine and its salts (Compounds of Formula I) & a-D-galactosamine and its salts (Compounds of Formula II) involves the use of starting reactant of Compounds of Formula IV. By employing this starting reactant (Compounds of Formula IV), number of steps involved in the synthesis of ß-D-galactosamine and its salts (Compounds of Formula I) & a-D-galactosamine and its salts (Compounds of Formula II) are significantly reduced to two. The present method of synthesis does not involve hazardous reaction conditions such as hydrogenation and use of expensive reagents such as Pd/C and biocatalyst as reported in the prior art. The present method eliminates the use of expensive starting materials and reagents and viz., D-tagatose, Pd(OH)2, biocatalyst and eliminates pyrophoric and explosive hydrogen gas, as reported in the prior art. The instant synthesis procedure significantly reduces process cycle time, which in turn reduces the cost. In conclusion, the synthesis procedure is industrially scalable, environmentally friendly and safe and very cost effective.
It is to be understood that the present invention is susceptible to modifications, changes and adaptations by those skilled in the art. Such modifications, changes, adaptations are intended to be within the scope of the present invention.
,CLAIMS:
1. A process of preparing ß-D-galactosamine and its salts represented by Formula I:

Wherein R1 is an acid salt;
Wherein the said process comprises the steps of:
i. Reacting Compound of Formula IV

Wherein, R2 is selected from a group comprising pivaloyl, benzoyl, acetyl, trichloroacetyl, chloromethylacetyl and benzene 1,2-dicarbonyl, wherein, each of them may be optionally substituted; R3 is selected from a group comprising pivaloyl, benzoyl, acetyl, trichloroacetyl and chloromethylacetyl, wherein, each of them may be optionally substituted;
With an acid to form a mixture of a/ß-D-galactosamine and its salts (Compound of Formula III);

ii. Dissolving the mixture of a/ß-D-galactosamine and its salts (Compound of Formula III) obtained in step (i) by stirring in an alcohol solvent optionally in combination with other non-alcohol solvents; and optionally heating the reaction mixture;
iii. Evaporating the solvent of step (ii), optionally slurrying the crude product, followed by filtering the precipitated product and drying to obtain ß-D-galactosamine and its salts (Compounds of Formula I).

2. The process as claimed in claim 1, wherein the acid at step (i) is selected from hydrochloric acid, hydrobromic acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid, tartaric acid or combinations thereof.

3. The process as claimed in claim 2, wherein the acid is hydrochloric acid.

4. The process as claimed in claim 1, wherein step (i) is carried out at a temperature ranging from -10 °C to about 150 °C for a period ranging from 30 minutes to 72 hours.

5. The process as claimed in claim 1, wherein the alcohol solvent at step (ii) is selected from methanol, ethanol, isopropanol, tert-butanol, n-butanol, 2-butanol, isoamyl alcohol, or combinations thereof.

6. The process as claimed in claim 5, wherein the alcohol solvent is methanol.

7. The process as claimed in claim 1, wherein the non-alcohol solvent at step (ii) is selected from water, acetone, toluene, benzene, acetonitrile, tetrahydrofuran, 2-methyl tetrahydrofuran, ethyl acetate, n-hexane, n-heptane, methyl tertiary butyl ether, dichloromethane, chloroform, carbon tetrachloride, chlorobenzene, cyclohexane, 1,2-dichloroethane, diethylene glycol, diethyl ether, diglyme, dimethyl formamide, dimethyl sulfoxide, 1,4-dioxane, ethylene glycol, glycerin, acetic acid, aqueous hydrochloric acid or combinations thereof.

8. The process as claimed in claim 7, wherein the non-alcohol solvent is water or aqueous hydrochloric acid.

9. The process as claimed in claim 1, wherein the ratio of alcohol solvent to non-alcohol solvent at step (ii) ranges from 100:1 to 10:1.

10. The process as claimed in claim 1, wherein the stirring at step (ii) is carried out at a temperature ranging from 10°C to 30°C for a period ranging from 1 to 36 hours.

11. A process of preparing a-D-galactosamine and its salts represented by Formula II:

Wherein R1 is an acid salt;
Wherein the said process comprises the steps of:
a. Reacting Compounds of Formula IV

Wherein, R2 is selected from a group comprising pivaloyl, benzoyl, acetyl, trichloroacetyl, chloromethylacetyl and benzene 1,2-dicarbonyl, wherein, each of them may be optionally substituted, R3 is selected from a group comprising pivaloyl, benzoyl, acetyl, trichloroacetyl and chloromethylacetyl, wherein, each of them may be optionally substituted;
With an acid to obtain a mixture of a/ß-D-galactosamine and its salts (Compounds of Formula III);

b. Dissolving a mixture of a/ß-D-galactosamine and its salts (Compounds of Formula III) obtained in step (a) by stirring in a water solvent;
c. Evaporating the water solvent of step (b), optionally slurrying the crude product, followed by filtering the precipitated product and drying to obtain a-D-galactosamine and its salts (Compounds of Formula II).

12. The process as claimed in claim 11, wherein the acid at step (a) is selected from hydrochloric acid, hydrobromic acid, sulphuric acid, phosphoric acid, nitric acid, perchloric acid, trifluoroacetic acid, trichloroacetic acid, citric acid, tartaric acid or combinations thereof.

13. The process as claimed in claim 12, wherein the acid is hydrochloric acid.

14. The process as claimed in claim 11, wherein step (a) is carried out at a temperature ranging from -10 °C to about 150 °C for a period ranging from 30 minutes to 72 hours.

15. The process as claimed in claim 11, wherein the stirring at step (b) is carried out at a temperature ranging from 10 °C to 30 °C for a period ranging from 1 to 36 hours.

16. A process of preparing mixture of a/ß-D-galactosamine and its salts of Formula III;

Wherein R1 is an acid salt;
Wherein the said process comprises the steps of:
Reacting Compounds of Formula IV

Wherein, R2 is selected from a group comprising pivaloyl, benzoyl, acetyl, trichloroacetyl, chloromethylacetyl and benzene 1,2-dicarbonyl, wherein, each of them may be optionally substituted, R3 is selected from a group comprising pivaloyl, benzoyl, acetyl, trichloroacetyl and chloromethylacetyl, wherein, each of them may be optionally substituted;
With an acid to obtain a mixture of a/ß-D-galactosamine and its salts (Compounds of Formula III).

17. A process of preparing ß-D-galactosamine and its salts represented by Formula I:

Wherein R1 is an acid salt;
Wherein the said process comprises the steps of:
Dissolving the mixture of a/ß-D-galactosamine and its salts (Compound of Formula III) by stirring in an alcohol solvent optionally in combination with other non-alcohol solvents; and optionally heating the reaction mixture;

Evaporating the solvent, optionally slurrying the crude product with the alcohol solvent, followed by filtering the precipitated product and drying to obtain ß-D-galactosamine and its salts (Compounds of Formula I).

18. A process of preparing a-D-galactosamine and its salts represented by Formula II:

Wherein R1 is an acid salt;
Wherein the said process comprises the steps of:
Dissolving a mixture of a/ß-D-galactosamine and its salts (Compounds of Formula III) by stirring in a water solvent;

Evaporating the water solvent, optionally slurrying the crude product followed by filtering the precipitated product and drying to obtain a-D-galactosamine and its salts (Compounds of Formula II).