Varenicline dioxo impurity

(1-Benzyl-2,5-dihydro-1H-pyrrol-3-yl)methanol

3-(2-(4-fluorophenyl)-2-oxoethyl)-1,6,7-trimethyl-8-(1-phenylethyl)-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione

3,4,9-trimethyl-1,7-bis[(3-methylphenyl)methyl]-1H,4H,6H,7H,8H,9H-[1,2,4]triazino[4,3-g]purine-6,8-dione

Ethyl 4-[2-(1,3,6,7-tetramethyl-2,4-dioxo-1,3,5-trihydro-4-imidazolino[1,2-h]p urin-8-yl)ethyl]piperazinecarboxylate

ethyl 2-(3-(2-chlorobenzyl)-1,6,7-trimethyl-2,4-dioxo-3,4-dihydro-1H-imidazo[2,1-f]purin-8(2H)-yl)acetate

ethyl 2-{7-[(ethoxycarbonyl)methyl]-3,4,9-trimethyl-6,8-dioxo-5,7,9-trihydro-4 H-1,2,4-triazino[4,3-h]purinyl}acetate

3-(2-fluorobenzyl)-8-(2-hydroxyphenyl)-1,6,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione

7-(4-chlorophenyl)-1-methyl-3-(3-methylbenzyl)oxazolo[2,3-f]purine-2,4(1H,3H)-dione

ethyl 2-(3-(2,5-dimethylbenzyl)-1,6,7-trimethyl-2,4-dioxo-3,4-dihydro-1H-imidazo[2,1-f]purin-8(2H)-yl)acetate

1,7-bis[(2-methylphenyl)methyl]-3,4,9-trimethyl-5,7,9-trihydro-4H-1,2,4-triazi no[4,3-h]purine-6,8-dione