There is an unknown alkaloid with the chemical formula $\mathrm{C_{10}H_{14}N_2}$; the unknown alkaloid can undergo the following reactions: (1) Heating the alkaloid in concentrated hydrochloric acid to 200~300°C produces $\mathrm{CH_3Cl}$; (2) Oxidizing the alkaloid with acidic potassium permanganate solution produces the product in Figure 1; (3) Reduction with sufficient hydrogen yields $\mathrm{C_{10}H_{20}N_2}$.

<MultiModal>![Fig. 1, the molecule in the figure is described by SMILES as: O=C(C1=CC=CN=C1)O](/media/uploads/33082ae5-eb2d-4838-aacb-26b2eaa2df48.png)</MultiModal>

Based on the above three reactions, what structural characteristics can be deduced for the alkaloid respectively? Further experiments show that the alkaloid has a five-membered ring. Deduce all possible structures of the alkaloid.

Which of the following option is correct:
有一未知生物碱, 化学式 $\mathrm{C_{10}H_{14}N_2}$; 该未知碱可发生如下反应:(1)将该生物碱在浓盐酸中加热至 200~300°C, 产生 $\mathrm{CH_3Cl}$; (2)用酸性高锰酸钾溶液氧化该生物碱, 产生图1产物;(3)被足量氢气还原得到 $\mathrm{C_{10}H_{20}N_2}$ 。

<MultiModal>![Fig. 1，图中分子以SMILES描述为：O=C(C1=CC=CN=C1)O](/media/uploads/33082ae5-eb2d-4838-aacb-26b2eaa2df48.png)</MultiModal>

根据以上三反应, 分别可得出该生物碱具有何种结构特点?进一步实验表明,该生物碱具有五元环,推测该生物碱所有可能的结构。

以下选项正确的是：
All other options are incorrect
The alkaloid is a secondary amine.
The alkaloid molecule contains a fused ring system of a five-membered ring and a six-membered ring.
This alkaloid has only one nitrogen atom with basicity.
The alkaloid may have three possible structures.
In every possible structure of this alkaloid, calculate the shortest number of covalent bonds separating the two nitrogen atoms; then the sum of the shortest number of covalent bonds separating the two nitrogen atoms in these structures is 9.
其他选项均不正确
该生物碱为二级胺
该生物碱分子内含有五元环与六元环的并环
该生物碱只有一个具有碱性的氮原子
该生物碱可能的结构有三种
该生物碱所有可能的每一个结构中，计算两个氮原子最短间隔共价键数，那么这几个结构中的两个氮原子最短间隔共价键数加和为9
(1) Hydrolysis with hydrochloric acid at high temperature yields $\mathrm{CH_3Cl}$, this step is the acidolysis of the group connected to the amino group, indicating that the alkaloid amino group is connected to at least one methyl group;

<Checkpoint>[The alkaloid amino group is connected to at least one methyl group](1)</Checkpoint>

(2) Oxidation with acidic potassium permanganate can selectively oxidize carbon-containing groups on the pyridine ring, while preserving the pyridine ring structure. The structure in Figure 1 is obtained, indicating that the alkaloid skeleton is a 3-substituted pyridine, and the atom connected to the pyridine is carbon.

<Checkpoint>[The alkaloid skeleton is a 3-substituted pyridine, and the atom connected to the pyridine is carbon](1)</Checkpoint>

(3) Reduction with sufficient hydrogen can saturate all unsaturated bonds within the molecule. According to the change in the molecular formula before and after reduction, the number of unsaturated bonds in the molecule can be calculated to be 3, entirely originating from the pyridine ring, indicating that there are no other unsaturated bonds within the molecule that can be reduced by hydrogen. At the same time, based on the carbon-hydrogen ratio of the reduced chemical formula, it can be deduced that the molecule contains two rings.

<Checkpoint>[There are no other unsaturated bonds within the molecule that can be reduced by hydrogen, contains two rings](1)</Checkpoint>

Based on the presence of a five-membered ring within the molecule, 5 out of the 10 carbon atoms in the molecule come from the pyridine ring, one from the methyl group on the amino group, and four carbon atoms remain. According to the results of (2), the five-membered ring cannot be a fused ring, it can only be a five-membered heterocycle composed of the remaining four carbons and one amino nitrogen atom. All possible structures of this alkaloid are shown in Figure 2 and Figure 3.

<Checkpoint>[The five-membered ring within the molecule is a nitrogen-containing five-membered ring](1)</Checkpoint>

<MultiModal>![Fig. 2，The molecule in the figure is described in SMILES as：CN1CCCC1C2=CC=CN=C2](/media/uploads/9caa9ace-3599-4eee-9e62-f17ad2390e18.png)</MultiModal>

<Checkpoint>[The first possible structure is: CN1CCCC1C2=CC=CN=C2](1)</Checkpoint>

<MultiModal>![Fig. 3，The molecule in the figure is described in SMILES as：CN1CCC(C1)C2=CC=CN=C2](/media/uploads/aef8867c-8b1c-4d62-9401-31820a68875c.png)</MultiModal>

<Checkpoint>[The second possible structure is: CN1CCC(C1)C2=CC=CN=C2](1)</Checkpoint>

This molecule is a tertiary amine, so option B is incorrect. The five-membered ring and the six-membered ring are not fused, so option C is incorrect. Both the pyridine nitrogen atom and the five-membered ring nitrogen atom are basic, so option D is incorrect. There are two possible structures, so option E is incorrect. In the two structures, the shortest number of covalent bonds between the two nitrogen atoms are 4 and 5, respectively, and the sum is 9, so option F is correct.
(1) 高温下盐酸水解得到$\mathrm{CH_3Cl}$，该步为与氨基相连基团的酸解，说明该生物碱氨基至少与一个甲基相连；

<Checkpoint>[该生物碱氨基至少与一个甲基相连](1)</Checkpoint>

(2) 酸性高锰酸钾氧化下可以选择性氧化吡啶环上含碳基团，而可以保留吡啶环结构。得到图1结构，说明该生物碱骨架为3-取代吡啶，且与吡啶相连的原子为碳。

<Checkpoint>[该生物碱骨架为3-取代吡啶，且与吡啶相连的原子为碳](1)</Checkpoint>

(3) 足量氢气还原可以饱和分子内的所有不饱和键，根据还原前后分子式变化可以算得分子不饱和键数为3，完全来着吡啶环，说明分子内不存在其他可被氢气还原的不饱和键。同时根据还原后的化学式的碳氢数量关系，可以推出分子内含有两个环。

<Checkpoint>[分子内不存在其他可被氢气还原的不饱和键，含有两个环](1)</Checkpoint>

根据分子内含有五元环，分子内10个碳原子5个来自吡啶环，一个来自氨基上的甲基，还剩四个碳。根据(2)结果知五元环不可能是并环，只能是剩余四个碳与一个氨基氮原子组成五元杂环，该生物碱所有可能的结构有图2和图3两种。

<Checkpoint>[分子内五元环为氮杂五元环](1)</Checkpoint>

<MultiModal>![Fig. 2，图中分子以SMILES描述为：CN1CCCC1C2=CC=CN=C2](/media/uploads/9caa9ace-3599-4eee-9e62-f17ad2390e18.png)</MultiModal>

<Checkpoint>[第一种可能的结构为：CN1CCCC1C2=CC=CN=C2](1)</Checkpoint>

<MultiModal>![Fig. 3，图中分子以SMILES描述为：CN1CCC(C1)C2=CC=CN=C2](/media/uploads/aef8867c-8b1c-4d62-9401-31820a68875c.png)</MultiModal>

<Checkpoint>[第二种可能的结构为：CN1CCC(C1)C2=CC=CN=C2](1)</Checkpoint>

该分子为三级胺，选项B错误。五元环与六元环非并环，选项C错误。吡啶氮原子和五元环氮原子均具有碱性，选项D错误。可能是结构有两种，选项E错误。两个结构中，两个氮原子最短间隔共价键数分别为4和5，加和为9，选项F正确。