List of Impurities of Palbociclib)

Sr.No

Structure

Chemical Name

Molecular Formula/Molecular Weight

Type

1.

5-bromo-N-cyclopentyl-2-(pyrrolidin-1-yl)pyrimidin-4-amine

M F: C₁₃H_19BrN₄

M W: 311.23

Process Impurity of [KSM-1]

2.

8-cyclopentyl-5-methyl-2-(pyrrolidin-1-yl)pyrido[2,3-d]pyrimidin-7(8H)-one

MF: C₁₇H₂₂N₄O

M W: 298.39

Process Impurity of KSM-2

3.

(E)-2-chloro-7-cyclopentyl-5-ethylidene-5,7-dihydro-6H-pyrrolo[2,3-d]pyrimidin-6-one

MF: C₁₃H₁₄ClN₃O

M W: 263.73

Process Impurity of KSM-2

4.

tert-butyl 4-(6-nitropyridin

-3-yl)piperazine-1-carboxylate

M F: C₁₄H₂₀N₄O₄

M W: 308.33

Intermediate  of KSM-2

5.

tert-butyl 4-(6-(hydroxyamino)pyridin-3-yl)piperazine-1-carboxylate

M F: C₁₄H₂₂N₄O₃

M W: 294.36

Process and Degradation impurity of KSM-2

6.

di-tert-butyl 4,4'-(diazene-1,2-diylbis(pyridine-6,3-diyl))(E)-bis(piperazine-1-carboxylate)

M F: C₂₈H₄₀N₈O₄

M W: 552.32

Process Impurity of KSM-2

7.

tert-butyl 4-(6-((8-cyclopentyl-6-(1-ethoxyvinyl)-5-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidin-2-yl)amino)pyridin-3-yl)piperazine-1-carboxylate

MF: C₃₁H₄₁N₇O₄

M W: 575.71

Boc Ethoxy Vinyl (N-2  Intermediate  of Palbociclib)

8.

tert-butyl 4-(6-((8-cyclopentyl-5-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidin-2-yl)amino)pyridin-3-yl)piperazine-1-carboxylate

MF: C₂₇H₃₅N₇O₃

MW:505.62

This is process impurity. If  unreacted is present in conversion into KSM-1 then on further coupling reaction of KSM-1with KSM-2 to form Boc Desacetyl impurity

9.

8-cyclopentyl-5-methyl-2-((5-(piperazin-1-yl)pyridin-2-yl)amino)-6-vinylpyrido[2,3-d]pyrimidin-7(8H)-one

MF: C₂₄H₂₉N₇O

MW:431.54

Process Impurity of Palbociclib

10.

6-acetyl-8-cyclopentyl-5-methyl-2-((5-(piperazin-1-yl)pyridin-2-yl)amino)pyrido[2,3-d]pyrimidin-7(8H)-one

MF: C₂₄H₂₉N₇O₃

MW:463.54

N-Oxide Impurity of Palbociclib

11.

tert-butyl 4-(6-((8-cyclopentyl-6-(2-ethoxyvinyl)-5-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidin-2-yl)amino)pyridin-3-yl)piperazine-1-carboxylate

MF: C₃₁H₄₁N₇O₄

MW:575.32

Resioisomer impurity is process impurity. This is the by-product of Heck Reaction

12.

8-cyclopentyl-5-methyl-2,6-bis((5-(piperazin-1-yl)pyridin-2-yl)amino)pyrido[2,3-d]pyrimidin-7(8H)-one

MF: C₃₁H₃₉N₁₁O

MW:581.73

This is process impurity (Dimer Impurity)