<MultiModal>![This image depicts a multicomponent organic chemical reaction: ClC1=CC=C(C=O)C=C1.NC2=CC=C(NC=C3)C3=C2.O=C(C4=C(N5)C=CC=C4)CC5=O>CCO>[X], with the reaction condition being reflux.](/media/uploads/b48149de-87ca-49bb-b487-b46f4ef4d369.png)</MultiModal>

The above multicomponent reaction produces product **X** through intermediates **P, Q, R** in sequence. 

It is known that: the formation of **P** involves a Knoevenagel condensation reaction, the formation of **Q** involves a Michael addition reaction with the newly formed bond not containing nitrogen atoms, the reaction from **R** to **X** eliminates one molecule of water, and the five-membered ring of the indole moiety in product **X** has no substituents.

Which of the following statements about intermediates **P, Q, R** and product **X** is correct:
<MultiModal>![本图描述了一个有机化学多组分反应：ClC1=CC=C(C=O)C=C1.NC2=CC=C(NC=C3)C3=C2.O=C(C4=C(N5)C=CC=C4)CC5=O>CCO>[X]，反应条件为reflux。](/media/uploads/b48149de-87ca-49bb-b487-b46f4ef4d369.png)</MultiModal>

上图的多组分反应生成产物**X**的过程依次经过中间体**P,Q,R**。已知：生成**P**的反应为Knoevenagel缩合反应，生成**Q**的反应为Micheal加成反应且新生成的键不含氮原子，**R**生成**X**的反应脱去一分子水，产物**X**的吲哚环的五元环无取代基。

下列关于中间体**P,Q,R**和产物**X**说法正确的是：
The intermediate **Q** has 18 hydrogen atoms in the $\mathrm{^1H ~NMR}$ spectrum measured in deuterated chloroform containing acidic impurities.
The intermediate **R** features adjacent $\mathrm{N-C-N}$ bonding.
The product **X** has five rings
The conjugated system of product **X** can extend over at least 12 non-hydrogen atoms.
None of the above statements are correct
There are 2 correct answers among options A to D
中间体**Q**在含有酸性杂质的氘代氯仿中测定的$\mathrm{^1H ~NMR}$有18个氢原子
中间体**R**存在相邻的$\mathrm{N-C-N}$键连关系
产物**X**具有五个环
产物**X**的共轭体系最少可波及12个非氢原子
以上说法均不正确
选项A到D中有2个正确
The Knoevenagel condensation occurs between an aldehyde/ketone and an active methylene compound. The substrate **p**-chlorobenzaldehyde is an aldehyde, and the C3 position of quinoline-2,4(1H,3H)-dione is an active methylene site, leading to the condensation reaction to form intermediate **P**, with the structural formula ClC(C=C1)=CC=C1/C=C2C(C3=CC=CC=C3NC/2=O)=O.

<Checkpoint>[The Knoevenagel condensation occurs between an aldehyde/ketone and an active methylene compound](1)</Checkpoint>

<Checkpoint>[The structural formula of **P** is ClC(C=C1)=CC=C1/C=C2C(C3=CC=CC=C3NC/2=O)=O](1)</Checkpoint>

**P** possesses an α-β unsaturated bond structure, which is a typical Michael acceptor, enabling nucleophilic addition by 5-aminoindole. Given the problem's hint that no new nitrogen-containing chemical bonds are formed and the indole five-membered ring in the final product lacks substituents, neither the amino group nor the 3-position of the indole acts as the nucleophilic site. In this case, the 4-position adjacent to the amino group is the most nucleophilic site, undergoing Michael addition with the substrate to yield intermediate **Q**, with the structure ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N)C4=C(O)C5=CC=CC=C5NC4=O.

<Checkpoint>[Neither the amino group nor the 3-position of the indole acts as the nucleophilic site; the 4-position adjacent to the amino group is the most nucleophilic site](1)</Checkpoint>

<Checkpoint>[The structure of **Q** is ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N)C4=C(O)C5=CC=CC=C5NC4=O](1)</Checkpoint>

At this stage, **Q** primarily exists in the enol form to satisfy aromaticity. The hydroxyl hydrogen of the enol form undergoes hydrogen-deuterium exchange in deuterated chloroform containing acidic impurities (thoroughly dried and purified deuterated chloroform can reveal the labile hydrogen), causing the peak to disappear in the NMR spectrum. Thus, only 17 hydrogens are observed in the NMR, making option A incorrect.

<Checkpoint>[**Q** primarily exists in the enol form to satisfy aromaticity](1)</Checkpoint>

<Checkpoint>[The hydroxyl hydrogen of the enol form undergoes hydrogen-deuterium exchange in deuterated chloroform](1)</Checkpoint>

**Q** contains both an amino group and a carbonyl group, enabling an intramolecular nucleophilic substitution reaction to form **R**. The reactivity of amides is inferior to that of ketones, so the structural formula of **R** is ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5C4(O)C6=CC=CC=C6NC5=O. This structure lacks adjacent N-C-N bonding, making option B incorrect.

<Checkpoint>[**Q** contains both an amino group and a carbonyl group, enabling an intramolecular nucleophilic substitution reaction](1)</Checkpoint>

<Checkpoint>[The structural formula of **R** is ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5C4(O)C6=CC=CC=C6NC5=O](1)</Checkpoint>

**R** undergoes dehydration and aromatization to yield the final product **X**, whose structural formula is ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5=C4C6=CC=CC=C6NC5=O.

<Checkpoint>[The structural formula of **X** is ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5=C4C6=CC=CC=C6NC5=O](1)</Checkpoint>

**X** contains six rings, making option C incorrect. The quinoline conjugated system in **X** includes at least 12 atoms, including the imine nitrogen atom, making option D correct.

<Checkpoint>[**X** contains six rings](1)</Checkpoint>

<Checkpoint>[The quinoline conjugated system in **X** includes at least 12 atoms, including the imine nitrogen atom](1)</Checkpoint>

In conclusion, option D is correct.

<MultiModal>![This figure depicts the structural formulas of the four unknown compounds involved in the problem. The structural formula of **P** is ClC(C=C1)=CC=C1/C=C2C(C3=CC=CC=C3NC/2=O)=O, **Q** is ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N)C4=C(O)C5=CC=CC=C5NC4=O, **R** is ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5C4(O)C6=CC=CC=C6NC5=O, and **X** is ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5=C4C6=CC=CC=C6NC5=O.](/media/uploads/d077567b-42e0-4f35-a9ce-1757cb9c1504.png)</MultiModal>
Knoevenagel缩合反应发生在醛/酮与活泼亚甲基化合物之间，底物对氯苯甲醛是醛，喹啉-2,4(1H,3H)-二酮的C3位是活泼亚甲基，从而发生缩合反应生成中间体**P**，结构式为ClC(C=C1)=CC=C1/C=C2C(C3=CC=CC=C3NC/2=O)=O。

<Checkpoint>[Knoevenagel缩合反应发生在醛/酮与活泼亚甲基化合物之间](1)</Checkpoint>

<Checkpoint>[**P**结构式为ClC(C=C1)=CC=C1/C=C2C(C3=CC=CC=C3NC/2=O)=O](1)</Checkpoint>


**P**拥有α-β不饱和键结构，为典型的Michael结构，从而可被5-氨基吲哚发生亲核加成；由于题设提示没有生成含氮的新化学键，且最终产物中吲哚五元环无取代基，因此氨基和吲哚的3号位不会作为亲核位点，此时氨基邻位4号位为最强的亲核位点，与底物发生Micheal加成得到中间体**Q**，结构为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N)C4=C(O)C5=CC=CC=C5NC4=O。

<Checkpoint>[氨基和吲哚的3号位不会作为亲核位点，此时氨基邻位4号位为最强的亲核位点](1)</Checkpoint>

<Checkpoint>[**Q**结构为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N)C4=C(O)C5=CC=CC=C5NC4=O](1)</Checkpoint>

此时**Q**主要存在形式为烯醇式以满足芳香性，而烯醇式的羟基氢在含有酸性杂质的氘代氯仿中会发生氢-氘交换（充分干燥和除杂的氘代氯仿是可以看到活泼氢的），在核磁谱图中峰会消失，从而核磁中只能看到17个氢，选项A错误。

<Checkpoint>[**Q**主要存在形式为烯醇式以满足芳香性](1)</Checkpoint>

<Checkpoint>[烯醇式的羟基氢在氘代氯仿中会发生氢-氘交换](1)</Checkpoint>

**Q**分子内有氨基和羰基，可发生分子内的亲核取代反应生成**R**；酰胺的反应性比酮差，因此**R**结构式为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5C4(O)C6=CC=CC=C6NC5=O。该结构中不存在相邻的N-C-N键连关系，选项B错误。

<Checkpoint>[**Q**分子内有氨基和羰基，可发生分子内的亲核取代反应](1)</Checkpoint>

<Checkpoint>[**R**结构式为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5C4(O)C6=CC=CC=C6NC5=O](1)</Checkpoint>

**R**脱去一分子水芳构化为产物**X**，故**X**结构式为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5=C4C6=CC=CC=C6NC5=O。

<Checkpoint>[**X**结构式为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5=C4C6=CC=CC=C6NC5=O](1)</Checkpoint>

**X**具有六个环，选项C错误；**X**的喹啉共轭体系至少有包含亚胺氮原子在内的12个原子，选项D正确。

<Checkpoint>[**X**具有六个环](1)</Checkpoint>

<Checkpoint>[**X**的喹啉共轭体系至少有包含亚胺氮原子在内的12个原子](1)</Checkpoint>

综上，选项D正确。

<MultiModal>![本图包含本题涉及到四种未知结构的结构式，**P**结构式为ClC(C=C1)=CC=C1/C=C2C(C3=CC=CC=C3NC/2=O)=O，**Q**结构为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N)C4=C(O)C5=CC=CC=C5NC4=O，**R**结构式为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5C4(O)C6=CC=CC=C6NC5=O，**X**结构式为ClC(C=C1)=CC=C1C(C2=C3C=CNC3=CC=C2N4)C5=C4C6=CC=CC=C6NC5=O。](/media/uploads/d077567b-42e0-4f35-a9ce-1757cb9c1504.png)</MultiModal>