[{"from": "human", "value": "Generate a molecule based on the given description. The molecule is the intermediate in the biosynthesis of vitamin B12 from uroporphyrinogen III in which three methyl groups have been introduced at positions 2, 7 and 20 of the tetrapyrrole framework and in which the carboxymethyl group at position 2 has been oxidised to form a lactone ring. It is a conjugate acid of a precorrin-3B(7-) and a precorrin-3B(6-)."}, {"from": "gpt", "value": "[C][C@@][C][C][=Branch1][C][=O][O][C@@][Ring1][=Branch1][C@@][Branch2][Branch2][=C][C][=C][Branch2][Branch2][Ring1][C][=Branch2][#Branch1][Branch2][=C][Branch1][Ring2][N][Ring1][Branch1][C][C][=C][Branch2][=Branch1][Branch1][C][=Branch2][Branch1][O][=C][Branch1][Ring2][N][Ring1][Branch1][/C][=C][/C@H1][Branch2][Ring2][Branch2][C@][Branch2][Ring1][O][/C][=Branch2][Ring1][Ring2][=C][/C][=Branch1][Branch1][=N][Ring2][Ring1][Branch1][C@H1][Ring2][Ring1][O][C][C][C][=Branch1][C][=O][O][/N][\\-Ring1][=C][Branch1][C][C][C][C][=Branch1][C][=O][O][C][C][C][=Branch1][C][=O][O][C][C][=Branch1][C][=O][O][C][C][C][=Branch1][C][=O][O][C][C][C][=Branch1][C][=O][O][C][C][=Branch1][C][=O][O][Branch1][C][C][O]"}]