[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule is a S-substituted analog of mercaptopurine and purine antagonist with cytostatic activity. Butocin inhibits purine nucleotide synthesis and DNA replication."}, {"from": "gpt", "value": "[C][C][O][C][=Branch1][C][=O][C][N][C][=Branch1][C][=O][C][C][C][C][S][C][=N][C][=N][C][=C][Ring1][=Branch1][N][C][=N][Ring1][Branch1]"}]