# US 11,111,228 B2 · Process for the preparation of pomalidomide and its purification

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- Number: US 11,111,228 B2
- Document ID: US11111228B2
- Status: Granted
- Kind: B2
- Application number: 16/311,782
- Filed: 2016-08-22
- Published: 2019-08-01
- Granted: 2021-09-07
- Earliest claimed: 2016-06-23
- Assignees: Natco Pharma Limited
- Applicants: Natco Pharma Limited
- Inventors: Durga Prasad Konakanchi; Buchappa Gongalla; Dharmendher Ragidi; Uma Naresh Babu Kotra; Kali Satya Bhujanga Rao Adibhatla; Venkaiah Chowdary Nannapaneni
- Web page: https://patentgrep.com/patent/US11111228B2

## CPC

- C07D 401/04: directly linked by a ring-member-to-ring-member bond
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

The present invention is related to an improved process for the preparation of Pomalidomide with higher yields and high purity. Particularly the present invention relates to form A preparation of Pomalidomide and its purification. wherein the present process doesn't involve use of dioxane solvent and avoids higher temperatures.

## Claims

### Claim 1

A process for the preparation of pomalidomide form A comprising the steps of:
a) reacting 3-nitrophthalic acid with acetic anhydride in presence of toluene to get 3-nitrophthalic anhydride,
b) reacting 3-nitrophthalic anhydride with 3-aminoglutarimide hydrochloride in presence of tri ethylamine and acetic acid solvent to get 2-(2, 6-dioxo-3-piperidyl)-4-nitro-isoindoline-1, 3-dione,
c) reducing the 2-(2, 6-dioxo-3-piperidyl)-4-nitro-isoindoline-1, 3-dione in the presence of Pd/C, dimethyl formamide solvent, and nitrogen, with hydrogen gas bubbled into the reaction mass, at 15° C. to 20° C. to get pomalidomide form A.

### Claim 2 (depends on 1)

A process according to claim 1, wherein the mole ratio of 3-nitrophthalic acid with acetic anhydride is 1:1.8 moles.

### Claim 3 (depends on 1)

A process according to claim 1 wherein the process further comprises steps for the purification of pomalidomide form A, comprising the steps of:
d) dissolving the pomalidomide form A obtained in step c) in dimethyl sulfoxide,
e) stirring the reaction mixture obtained in step d) at room temperature,
f) adding the reaction mass obtained in step e) to water,
g) stirring the reaction mass obtained in step f) at room temperature, and
h) isolating pure pomalidomide form A.

### Claim 4 (depends on 2)

A process according to claim 2 wherein the process further comprises steps for the purification of pomalidomide form A, comprising the steps of:
d) dissolving the pomalidomide form A obtained in step c) in dimethyl sulfoxide,
e) stirring the reaction mixture obtained in step d) at room temperature,
f) adding the reaction mass obtained in step e) to water,
g) stirring the reaction mass obtained in step f) at room temperature, and
h) isolating pure pomalidomide form A.