entecavir and its Impurities
It is a derivative of Etofylline and a Entecavir analog which is also known in the name of nucleoside. It is an antiviral drug used in the treatment of HIV/AIDS.. Reference standards of Entecavir API, and its pharmacopeial, non pharmacopeial impurities, and stable isotopes are listed below


Cyclopentanemethanol, 5-[2-amino-6-(phenylmethoxy)-9H-purin-9-yl]-3-(dimethylphenylsilyl)-1-hydroxy-2-[(phenylmethoxy)methyl]-, (1S,2S,3S,5S)-
Cyclopentanemethanol, 5-[2-amino-6-(phenylmethoxy)-9H-purin-9-yl]-3-(dimethylphenylsilyl)-1-hydroxy-2-[(phenylmethoxy)methyl]-, (1S,2S,3S,5S)-
Catalogue No.:PA 05 57570
CAS :
649761-23-9
Molecular Formula : C34H39N5O4Si
Molecular Weight : 609.79

![5-[[2-Amino-5-[2-(4-chlorophenyl)diazenyl]-6-metho PA STI 005520](https://www.pharmaffiliates.com/pimages/PASTI005520.jpg)
5-[[2-Amino-5-[2-(4-chlorophenyl)diazenyl]-6-methoxy-4-pyrimidinyl]amino-13C2, 15N]-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]-cyclopentanol
5-[[2-Amino-5-[2-(4-chlorophenyl)diazenyl]-6-methoxy-4-pyrimidinyl]amino-13C2, 15N]-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]-cyclopentanol
Catalogue No.:PA STI 005520
CAS :
NA
Molecular Formula : C2913C2H33ClN515NO4
Molecular Weight : 592.06

![5-[(2-Amino-6-chloro-4-pyrimidinyl-13C2)amino]-3-( PA STI 005530](https://www.pharmaffiliates.com/pimages/PASTI005530.jpg)
5-[(2-Amino-6-chloro-4-pyrimidinyl-13C2)amino]-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]cyclopentanol
5-[(2-Amino-6-chloro-4-pyrimidinyl-13C2)amino]-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]cyclopentanol
Catalogue No.:PA STI 005530
CAS :
NA
Molecular Formula : C2213C2H27ClN4O3
Molecular Weight : 456.93


(1S,2S,3S,5S)-5-((2-Amino-6-chloro-5-((E)-(4-chlorophenyl)diazenyl)pyrimidin-4-yl)amino-15N)-3-(benzyloxy)-2-((benzyloxy)methyl)cyclopentan-1-ol-1,2-13C2
(1S,2S,3S,5S)-5-((2-Amino-6-chloro-5-((E)-(4-chlorophenyl)diazenyl)pyrimidin-4-yl)amino-15N)-3-(benzyloxy)-2-((benzyloxy)methyl)cyclopentan-1-ol-1,2-13C2
Catalogue No.:PA STI 005690
CAS :
1207872-65-8
Molecular Formula : C2813C2H30Cl2N515NO3
Molecular Weight : 596.48


(1S,2S,3S,5S)-5-(2-Amino-6-methoxy-9H-purin-9-yl)-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]-cyclopentanol-13C2,15N
(1S,2S,3S,5S)-5-(2-Amino-6-methoxy-9H-purin-9-yl)-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]-cyclopentanol-13C2,15N
Catalogue No.:PA STI 006150
CAS :
NA
Molecular Formula : C2413C2H29N415NO4
Molecular Weight : 478.52


5-[(4-Methoxyphenyl)-diphenylmethylamino-6-methoxy-9H-purin-9-yl]-13C2, 15N-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]-cyclopentanol
5-[(4-Methoxyphenyl)-diphenylmethylamino-6-methoxy-9H-purin-9-yl]-13C2, 15N-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]-cyclopentanol
Catalogue No.:PA STI 059490
CAS :
NA
Molecular Formula : C4413C2H45N415NO5
Molecular Weight : 750.86


Entecavir Related Compound A (9-[(1S,3R,4S)-4-Dimethylphenylsilyl-3-(benzyloxymethyl)-2-methylenecy (1235977)
Entecavir Related Compound A (9-[(1S,3R,4S)-4-Dimethylphenylsilyl-3-(benzyloxymethyl)-2-methylenecy (1235977)
Catalogue No.:PA USP1235977
CAS :
649761-24-0
Molecular Formula : NA
Molecular Weight : NA


Entecavir System Suitability Mixture (A mixture containing entecavir 1-epimer (0.1%), entecavir (99 (1235988)
Entecavir System Suitability Mixture (A mixture containing entecavir 1-epimer (0.1%), entecavir (99 (1235988)
Catalogue No.:PA USP1235988
CAS :
NA
Molecular Formula : NA
Molecular Weight : NA


((1R,3S,5S)-5-Acetoxy-3-(2-amino-6-oxo-1H-purin-9(6H)-yl)-2-methylenecyclopentyl)methyl Acetate
((1R,3S,5S)-5-Acetoxy-3-(2-amino-6-oxo-1H-purin-9(6H)-yl)-2-methylenecyclopentyl)methyl Acetate
Catalogue No.:PAI 05 004010
CAS :
NA
Molecular Formula : C16H19N5O5
Molecular Weight : 361.35


((1R,3S,5S)-5-Acetoxy-3-(2-amino-8-bromo-6-oxo-1H-purin-9(6H)-yl)-2-methylenecyclopentyl)methyl Acetate
((1R,3S,5S)-5-Acetoxy-3-(2-amino-8-bromo-6-oxo-1H-purin-9(6H)-yl)-2-methylenecyclopentyl)methyl Acetate
Catalogue No.:PAI 05 004020
CAS :
NA
Molecular Formula : C16H18BrN5O5
Molecular Weight : 440.25


2-Amino-1,9-dihydro-9-[(1R,3R,4R)-2-methylene-4-(phenylmethoxy)-3-[(phenylmethoxy)methyl]cyclopentyl]-6H-purin-6-one
2-Amino-1,9-dihydro-9-[(1R,3R,4R)-2-methylene-4-(phenylmethoxy)-3-[(phenylmethoxy)methyl]cyclopentyl]-6H-purin-6-one
Catalogue No.:PA 05 57610
CAS :
1354695-84-3
Molecular Formula : C26H27N5O3
Molecular Weight : 457.52


2-Amino-8-hydroxy-9-((1S,3R,4S)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl)-1,9-dihydro-6H-purin-6-one
2-Amino-8-hydroxy-9-((1S,3R,4S)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl)-1,9-dihydro-6H-purin-6-one
Catalogue No.:PA 05 57600
CAS :
NA
Molecular Formula : C12H15N5O4
Molecular Weight : 293.28


2-amino-9-((1R,3S,4R)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl)-8-methoxy-1,9-dihydro-6H-purin-6-one
2-amino-9-((1R,3S,4R)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl)-8-methoxy-1,9-dihydro-6H-purin-6-one
Catalogue No.:PA 32 0171002
CAS :
2203740-23-0
Molecular Formula : C13H17N5O4
Molecular Weight : 307.31


2-amino-9-((3aR,4R,6S,6aS)-3a,6-dihydroxyhexahydro-1H-cyclopenta[c]furan-4-yl)-1,9-dihydro-6H-purin-6-one
2-amino-9-((3aR,4R,6S,6aS)-3a,6-dihydroxyhexahydro-1H-cyclopenta[c]furan-4-yl)-1,9-dihydro-6H-purin-6-one
Catalogue No.:PA 32 0171003
CAS :
1391053-94-3
Molecular Formula : C12H15N5O4
Molecular Weight : 293.28


2-amino-9-((1R,3S,4R)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl)-7,9-dihydro-1H-purine-6,8-dione
2-amino-9-((1R,3S,4R)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl)-7,9-dihydro-1H-purine-6,8-dione
Catalogue No.:PA 32 0171004
CAS :
2204369-23-1
Molecular Formula : C12H15N5O4
Molecular Weight : 293.28


(1S,2S,3S,5S)-3-(benzyloxy)-5-(6-(benzyloxy)-2-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-2-((benzyloxy)methyl)cyclopentan-1-ol
(1S,2S,3S,5S)-3-(benzyloxy)-5-(6-(benzyloxy)-2-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-2-((benzyloxy)methyl)cyclopentan-1-ol
Catalogue No.:PA 32 0171005
CAS :
142217-78-5
Molecular Formula : C52H49N5O5
Molecular Weight : 823.99


(2R,3S,5S)-3-(benzyloxy)-5-(6-(benzyloxy)-2-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-2-((benzyloxy)methyl)cyclopentan-1-one
(2R,3S,5S)-3-(benzyloxy)-5-(6-(benzyloxy)-2-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-2-((benzyloxy)methyl)cyclopentan-1-one
Catalogue No.:PA 32 0171006
CAS :
142217-79-6
Molecular Formula : C52H47N5O5
Molecular Weight : 821.98


6-(benzyloxy)-9-((1S,3R,4S)-4-(benzyloxy)-3-((benzyloxy)methyl)-2-methylenecyclopentyl)-N-((4-methoxyphenyl)diphenylmethyl)-9H-purin-2-amine
6-(benzyloxy)-9-((1S,3R,4S)-4-(benzyloxy)-3-((benzyloxy)methyl)-2-methylenecyclopentyl)-N-((4-methoxyphenyl)diphenylmethyl)-9H-purin-2-amine
Catalogue No.:PA 32 0171007
CAS :
142217-80-9
Molecular Formula : C53H49N5O4
Molecular Weight : 820.01


(1S,2S,3R,5R)-3-(benzyloxy)-5-(6-(benzyloxy)-2-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-2-((benzyloxy)methyl)cyclopentan-1-ol
(1S,2S,3R,5R)-3-(benzyloxy)-5-(6-(benzyloxy)-2-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-2-((benzyloxy)methyl)cyclopentan-1-ol
Catalogue No.:PA 32 0171009
CAS :
1354695-74-1
Molecular Formula : C52H49N5O5
Molecular Weight : 823.99


2-Amino-9-((1S,3R,4R)-4-(benzyloxy)-3-((benzyloxy)methyl)-2-methylenecyclopentyl)-1,9-dihydro-6H-purin-6-one
2-Amino-9-((1S,3R,4R)-4-(benzyloxy)-3-((benzyloxy)methyl)-2-methylenecyclopentyl)-1,9-dihydro-6H-purin-6-one
Catalogue No.:PA 32 0171010
CAS :
1354695-85-4
Molecular Formula : C26H27N5O3
Molecular Weight : 457.53


6-(Benzyloxy)-9-((1S,3R,4S)-4-(benzyloxy)-3-((benzyloxy)methyl)-2-methylenecyclopentyl)-N-trityl-9H-purin-2-amine
6-(Benzyloxy)-9-((1S,3R,4S)-4-(benzyloxy)-3-((benzyloxy)methyl)-2-methylenecyclopentyl)-N-trityl-9H-purin-2-amine
Catalogue No.:PA 32 0171011
CAS :
1661867-19-1
Molecular Formula : C52H47N5O3
Molecular Weight : 789.98


(1S,2S,3S,5S)-3-(Benzyloxy)-5-(6-(benzyloxy)-2-(tritylamino)-9H-purin-9-yl)-2-((benzyloxy)methyl)cyclopentan-1-ol
(1S,2S,3S,5S)-3-(Benzyloxy)-5-(6-(benzyloxy)-2-(tritylamino)-9H-purin-9-yl)-2-((benzyloxy)methyl)cyclopentan-1-ol
Catalogue No.:PA 32 0171012
CAS :
1345339-53-8
Molecular Formula : C51H47N5O4
Molecular Weight : 793.97


(1S,2S,3S,5S)-5-(2-amino-6-(benzyloxy)-9H-purin-9-yl)-3-(benzyloxy)-2-((benzyloxy)methyl)cyclopentan-1-ol
(1S,2S,3S,5S)-5-(2-amino-6-(benzyloxy)-9H-purin-9-yl)-3-(benzyloxy)-2-((benzyloxy)methyl)cyclopentan-1-ol
Catalogue No.:PA 32 0171013
CAS :
142217-77-4
Molecular Formula : C32H33N5O4
Molecular Weight : 551.65


(1S,2S,3S,5S)-5-[[2-Amino-5-[2-(4-chlorophenyl)diazenyl]-6-methoxy-4-pyrimidinyl]amino]-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]-cyclopentanol
(1S,2S,3S,5S)-5-[[2-Amino-5-[2-(4-chlorophenyl)diazenyl]-6-methoxy-4-pyrimidinyl]amino]-3-(phenylmethoxy)-2-[(phenylmethoxy)methyl]-cyclopentanol
Catalogue No.:PA 32 0171017
CAS :
NA
Molecular Formula : C31H33ClN6O4
Molecular Weight : 589.08