(6aR,9aS)-2-(cyclopropylmethyl)-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylmethyl)cyclopent[4,5]imidazo[2,1-b]purin-4(3H)-one

5'-methyl-2'-(biphenylmethyl)-3'-(phenylmethyl)spiro[cyclopentane-1,7'(8'H)-[3H]imidazo[2,1-b]purin]-4'(5'H)-one

(6aR,9aS)-2-[(N,N-dimethylamino)methyl]-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylmethyl)cyclopent[4,5]imidazo[2,1-b]purin-4(3H)-one

7,8-Dibenzyl-2-chloro-1-methyl-1,7-dihydro-purin-6-one

(6aR,9aS)-2-formyl-cis-5,6a,7,8,9,9a-hexahydro-5-methyl-3-(phenylmethyl)cyclopent[4,5]imidazo[2,1-b]purin-4(3H)-one