<MultiModal>![[O-][N+]1=C[C@@H](O)CC1 reacting with O=C(/C=C\C(O)=O)OC under $PPh_3, DEAD, THF$ conditions to generate $\bf X$, and $\bf X$ reacting under $H_2, 20\% Pd(OH)_2/C, MeOH$ conditions to generate $\bf Y$](/media/uploads/29b12dbf-7854-438d-8d0a-d8dfe07f6d5e.png)</MultiModal>

Known:
1. $\bf Y$ contains three rings and contains 8 carbon atoms.
2. In the first step reaction, $\rm PPh_3, DEAD$ are in large excess.
3. The formation of $\bf Y$ from $\bf X$ proceeds through two important electrically neutral intermediates $\bf 1，2$.

Which of the following statements is correct:
<MultiModal>![[O-][N+]1=C[C@@H](O)CC1与O=C(/C=C\C(O)=O)OC在$PPh_3, DEAD, THF$条件下反应生成$\bf X$，$\bf X$在$H_2, 20\% Pd(OH)_2/C, MeOH$条件下生成$\bf Y$](/media/uploads/29b12dbf-7854-438d-8d0a-d8dfe07f6d5e.png)</MultiModal>

已知：
1. $\bf Y$含有三个环，且含有8个碳原子。
2. 第一步反应中的$\rm PPh_3, DEAD$为大过量。
3. 由$\bf X$生成$\bf Y$经过两个重要的电中性中间体$\bf 1，2$。

本题要求立体化学。

下列说法正确的是：
All other options are incorrect
The number of chiral centers in $\bf X$ and $\bf Y$ is inconsistent.
$\bf X$ contains at least two S-configuration chiral carbon atoms
$\bf X$, $\bf 1, 2$ both contain three rings.
Under strongly alkaline conditions, $\bf Y$ undergoes heated hydrolysis, and the hydrolysis product has two rings.
$\bf Y$ possesses a six-membered ring
The chiral carbon atoms with R configuration are more than those with S configuration in $\bf Y$.
其他选项均不正确
$\bf X$与$\bf Y$的手性中心数目不一致
$\bf X$中至少含有两个S构型的手性碳原子
$\bf X$，$\bf 1，2$均含有三个环
在强碱性条件加热水解$\bf Y$，得到的水解产物具有两个环
$\bf Y$具有六元环
$\bf Y$中R构型的手性碳原子多于S构型的手性碳原子
The first step added $\rm PPh_3, DEAD$, which are obvious Mitsunobu reaction conditions. The reaction site is obviously the alcohol hydroxyl group of the five-membered ring substrate and the carboxyl group of another molecule of the substrate, generating an ester. According to the stereochemical requirements of the Mitsunobu reaction, the stereoconfiguration of the alcohol hydroxyl group will be inverted; the resulting ester structure is [O-][N+]1=C[C@H](OC(/C=C\C(OC)=O)=O)CC1.

<Checkpoint>[The first step added $\rm PPh_3, DEAD$, which are Mitsunobu reaction conditions](1)</Checkpoint>

<Checkpoint>[The stereochemical requirements of the Mitsunobu reaction require the stereoconfiguration of the alcohol hydroxyl group to be inverted](1)</Checkpoint>

<Checkpoint>[The ester structure is [O-][N+]1=C[C@H](OC(/C=C\C(OC)=O)=O)CC1](1)</Checkpoint>

According to the structure of $\bf Y$ containing three rings and an ester, the molecule contains a 1,3-dipole and an electron-deficient double bond, which can obviously undergo an intramolecular [1,3] dipolar cycloaddition reaction to obtain two five-membered rings; the stereochemical requirements of this reaction are that since the double bond is in the cis conformation, the resulting substituents should be on the same side. Therefore, the structure of $\bf X$ is [H][C@]12[C@@H](C(OC)=O)ON3CC[C@@H](OC2=O)[C@]31[H]. This structure contains four chiral carbon atoms, three R and one S configuration, option C is incorrect.

<Checkpoint>[Intramolecular [1,3] dipolar cycloaddition reaction occurs to obtain two five-membered rings](1)</Checkpoint>

<Checkpoint>[The double bond is in the cis conformation, and the resulting substituents should be on the same side](1)</Checkpoint>

<Checkpoint>[The structure of $\bf X$ is [H][C@]12[C@@H](C(OC)=O)ON3CC[C@@H](OC2=O)[C@]31[H], with three R and one S configuration chiral carbon atoms](1)</Checkpoint>

$\bf X$ reacts with hydrogen, and obviously the heteroatom bond $\rm N-O$ is reduced first; therefore, the intermediate $\bf 1$ structure is [H][C@@]1([C@@]2([H])NCC[C@H]2OC1=O)[C@H](O)C(OC)=O.

<Checkpoint>[The heteroatom bond $\rm N-O$ is reduced first](1)</Checkpoint>

<Checkpoint>[The intermediate $\bf 1$ structure is [H][C@@]1([C@@]2([H])NCC[C@H]2OC1=O)[C@H](O)C(OC)=O](1)</Checkpoint>

The final product has three rings, so $\bf 1$ to $\bf 2$ is obviously still a ring-forming reaction. Observing the structure, it can be seen that it should be the reaction of the amino group with the ester group to obtain a five-membered ring amide. Therefore, the intermediate $\bf 2$ is a nucleophilic addition tetrahedral intermediate, with the structure [H][C@]12[C@H](O)C(O)(OC)N3CC[C@@H](OC2=O)[C@]31[H].

<Checkpoint>[The amino group reacts with the ester group to obtain a five-membered ring amide](1)</Checkpoint>

<Checkpoint>[The intermediate $\bf 2$ is a nucleophilic addition tetrahedral intermediate, with the structure [H][C@]12[C@H](O)C(O)(OC)N3CC[C@@H](OC2=O)[C@]31[H]](1)</Checkpoint>

$\bf Y$ is a five-membered ring amide, with the structure [H][C@]12[C@H](O)C(N3CC[C@@H](OC2=O)[C@]31[H])=O. $\bf Y$ contains three five-membered rings. The chiral carbon atoms in the process of generating $\bf Y$ do not change, so the configuration remains unchanged, still three R and one S configuration, option G is correct, B is incorrect, and F is incorrect. $\bf 1$ contains only two rings, option D is incorrect.

<Checkpoint>[$\bf Y$ is a five-membered ring amide, with the structure [H][C@]12[C@H](O)C(N3CC[C@@H](OC2=O)[C@]31[H])=O](1)</Checkpoint>

<Checkpoint>[The chiral carbon atoms in the process of generating $\bf Y$ do not change, still three R and one S configuration](1)</Checkpoint>

$\bf Y$ hydrolyzes the ester and amide groups under basic heating conditions, so only one tetrahydropyrrole ring structure will be retained in the three rings, option E is incorrect.

<Checkpoint>[$\bf Y$ hydrolyzes the ester and amide groups under basic heating conditions, so only one tetrahydropyrrole ring structure will be retained in the three rings](1)</Checkpoint>
第一步加入了$\rm PPh_3, DEAD$，为很明显的Mitsunobu反应条件。反应位点很明显为五元环底物的醇羟基和另一分子底物的羧基，生成酯。根据Mitsunobu反应的立体化学要求，醇羟基的立体构型会发生反转；得到的酯结构为[O-][N+]1=C[C@H](OC(/C=C\C(OC)=O)=O)CC1。

<Checkpoint>[第一步加入了$\rm PPh_3, DEAD$，为Mitsunobu反应条件](1)</Checkpoint>

<Checkpoint>[Mitsunobu反应的立体化学要求，醇羟基的立体构型会发生反转](1)</Checkpoint>

<Checkpoint>[酯结构为[O-][N+]1=C[C@H](OC(/C=C\C(OC)=O)=O)CC1](1)</Checkpoint>

根据$\bf Y$含有三个环和酯的结构，分子内含有1，3偶极体和缺电子双键，很明显可以发生分子内[1,3]偶极环加成反应得到两个五元环；该反应的立体化学要求，由于双键为顺式构象，得到的取代基应当处于同侧。因此$\bf X$结构为[H][C@]12[C@@H](C(OC)=O)ON3CC[C@@H](OC2=O)[C@]31[H]。该结构含有四个手性碳原子，三个R一个S构型，选项C错误。

<Checkpoint>[发生分子内[1,3]偶极环加成反应得到两个五元环](1)</Checkpoint>

<Checkpoint>[双键为顺式构象，得到的取代基应当处于同侧](1)</Checkpoint>

<Checkpoint>[$\bf X$结构为[H][C@]12[C@@H](C(OC)=O)ON3CC[C@@H](OC2=O)[C@]31[H]，具有三个R一个S构型的手性碳原子](1)</Checkpoint>

$\bf X$与氢气反应，很明显杂原子键$\rm N-O$首先被还原；因此中间体$\bf 1$结构为[H][C@@]1([C@@]2([H])NCC[C@H]2OC1=O)[C@H](O)C(OC)=O。

<Checkpoint>[杂原子键$\rm N-O$首先被还原](1)</Checkpoint>

<Checkpoint>[中间体$\bf 1$结构为[H][C@@]1([C@@]2([H])NCC[C@H]2OC1=O)[C@H](O)C(OC)=O](1)</Checkpoint>

最终产物为三个环，因此$\bf 1$到$\bf 2$很明显仍旧为成环反应，观察结构可知应当为氨基与酯基反应得到五元环酰胺。因此中间体$\bf 2$为亲核加成四面体中间体，结构为[H][C@]12[C@H](O)C(O)(OC)N3CC[C@@H](OC2=O)[C@]31[H]。

<Checkpoint>[氨基与酯基反应得到五元环酰胺](1)</Checkpoint>

<Checkpoint>[中间体$\bf 2$为亲核加成四面体中间体，结构为[H][C@]12[C@H](O)C(O)(OC)N3CC[C@@H](OC2=O)[C@]31[H]](1)</Checkpoint>

$\bf Y$为五元环酰胺，结构为[H][C@]12[C@H](O)C(N3CC[C@@H](OC2=O)[C@]31[H])=O。$\bf Y$含有三个五元环，生成$\bf Y$的过程手性碳原子无变化，故构型维持不变，仍旧为三个R一个S构型，选项G正确，B错误，F错误。$\bf 1$只含有两个环，选项D错误。

<Checkpoint>[$\bf Y$为五元环酰胺，结构为[H][C@]12[C@H](O)C(N3CC[C@@H](OC2=O)[C@]31[H])=O](1)</Checkpoint>

<Checkpoint>[生成$\bf Y$的过程手性碳原子无变化，仍旧为三个R一个S构型](1)</Checkpoint>

$\bf Y$在碱性加热条件水解酯基和酰胺，因此三个环只会保留一个四氢吡咯环结构，选项E错误。

<Checkpoint>[$\bf Y$在碱性加热条件水解酯基和酰胺，因此三个环只会保留一个四氢吡咯环结构](1)</Checkpoint>