Speculate on the structures and reaction mechanisms of $\mathbf{E}$ and $\mathbf{F}$ in Figure 1.

<MultiModal>![Fig. 1, the figure shows a two-step reaction. The first step is described by SMILES as: CC1=CC=C(N(S(=O)(C(F)(F)F)=O)CCC=C)O1>>[[E]], reaction conditions are toluene, 130°C, 4h. The second step is described by SMILES as: [[E]]>>[[F]], reaction conditions are $\mathrm{LiAlH_4, Et_2O, reflux, 4h}$.](/media/uploads/e7874025-ff6f-4483-9928-0df6150140cb.png)</MultiModal>

The following statements are made:

1.  $\mathbf{E}$ contains two rings of six members or less.
2.  The formation of $\mathbf{E}$ involves an intermediate containing 3 five-membered rings.
3.  The mechanism for the formation of $\mathbf{E}$ is an ionic mechanism.
4.  $\mathbf{F}$ can eliminate one molecule of hydrogen gas to form a stable conjugated system.

Which of the following options contains all correct statements and the greatest number of correct statements:
推测图1 $\mathbf{E}$和$\mathbf{F}$的结构及反应机理。

<MultiModal>![Fig. 1，图中为两步反应，第一步以SMILES描述为：CC1=CC=C(N(S(=O)(C(F)(F)F)=O)CCC=C)O1>>[[E]]，反应条件为toluene，130°C，4h。第二步以SMILES描述为：[[E]]>>[[F]]，反应条件为$\mathrm{LiAlH_4, Et_2O, reflux, 4h}$。](/media/uploads/e7874025-ff6f-4483-9928-0df6150140cb.png)</MultiModal>

有以下说法：

1. $\mathbf{E}$中含有两个六元及以下的环
2. 生成$\mathbf{E}$的过程中经历了含有3个五元环的中间体
3. 生成$\mathbf{E}$的机理为离子机理
4. $\mathbf{F}$可以脱去一分子氢气生成稳定的共轭体系

以下选项中说法全部正确且正确数量最多的为：
All other options are incorrect
1
2
3
4
1,2
1,3
1,4
2,3
2,4
3,4
1,2,3
1,2,4
1,3,4
2,3,4
1,2,3,4
其他选项均不正确
1
2
3
4
1,2
1,3
1,4
2,3
2,4
3,4
1,2,3
1,2,4
1,3,4
2,3,4
1,2,3,4
Step one: The high temperature represents typical conditions for a pericyclic reaction. Observing the molecular structure, it can be found that the furan ring can act as a diene, while the terminal double bond can act as a dienophile. The two undergo a D-A reaction to generate the polycyclic intermediate shown in Figure 2:

<MultiModal>![Fig. 2, the molecule in the figure is described by SMILES as: CC1(C=C2)OC32N(S(=O)(C(F)(F)F)=O)CCC3C1
](/media/uploads/9cbf75b7-c097-4f1c-9bdc-6f799ebab73e.png)</MultiModal>

<Checkpoint>[D-A reaction generates the intermediate shown in Figure 2: <MultiModal>![Fig. 2, the molecule in the figure is described by SMILES as: CC1(C=C2)OC32N(S(=O)(C(F)(F)F)=O)CCC3C1 ](/media/uploads/9cbf75b7-c097-4f1c-9bdc-6f799ebab73e.png)</MultiModal>](1)</Checkpoint>

This intermediate can further open the bridged ring structure and eliminate one molecule of water to form a benzene ring structure, which is the structure of $\mathbf{E}$, as shown in Figure 3:

<MultiModal>![Fig. 3, the molecule in the figure is described by SMILES as: O=S(N1CCC2=C1C=CC(C)=C2)(C(F)(F)F)=O](/media/uploads/64bcdf9b-68b4-46f7-ade9-0035e49e9853.png)</MultiModal>

<Checkpoint>[Open the bridged ring structure and eliminate water to form a benzene ring. The structure of $\mathbf{E}$ is shown in Figure 3:  <MultiModal>![Fig. 3, the molecule in the figure is described by SMILES as: O=S(N1CCC2=C1C=CC(C)=C2)(C(F)(F)F)=O](/media/uploads/64bcdf9b-68b4-46f7-ade9-0035e49e9853.png)</MultiModal>](1)</Checkpoint>

$\mathbf{E}$ contains one six-membered ring and one five-membered ring, so statement 1 is correct.
The formation of $\mathbf{E}$ involves the intermediate shown in Figure 2, which contains three five-membered rings (and one six-membered ring), so statement 2 is correct. The formation of $\mathbf{E}$ is a D-A reaction with a pericyclic mechanism, so statement 3 is incorrect.

$\mathbf{E}$ is reduced by lithium aluminum hydride to remove the trifluoromethanesulfonyl group, yielding $\mathbf{F}$, with the structure shown in Figure 4:

<MultiModal>![Fig. 4, the molecule in the figure is described by SMILES as: CC1=CC2=C(C=C1)NCC2](/media/uploads/497e3917-73ef-4445-b04e-e882d419bbeb.png)</MultiModal>

<Checkpoint>[The trifluoromethanesulfonyl group is reduced by lithium aluminum hydride to give $\mathbf{F}$ as shown in Figure 4:  <MultiModal>![Fig. 4, the molecule in the figure is described by SMILES as: CC1=CC2=C(C=C1)NCC2](/media/uploads/497e3917-73ef-4445-b04e-e882d419bbeb.png)</MultiModal>](1)</Checkpoint>

$\mathbf{F}$ can eliminate one molecule of hydrogen to form an aromatic indole ring, so statement 4 is correct.
第一步高温为典型周环反应条件，观察分子结构可以发现，呋喃环可以作为双烯体，而端基双键可以作为单烯体，二者发生D-A反应生成图2多环中间体：

<MultiModal>![Fig. 2，图中分子以SMILES描述为：CC1(C=C2)OC32N(S(=O)(C(F)(F)F)=O)CCC3C1
](/media/uploads/9cbf75b7-c097-4f1c-9bdc-6f799ebab73e.png)</MultiModal>

<Checkpoint>[发生D-A反应生成图2中间体：<MultiModal>![Fig. 2，图中分子以SMILES描述为：CC1(C=C2)OC32N(S(=O)(C(F)(F)F)=O)CCC3C1 ](/media/uploads/9cbf75b7-c097-4f1c-9bdc-6f799ebab73e.png)</MultiModal>](1)</Checkpoint>

该中间体可以进一步解开桥环结构，消除一分子水形成苯环结构，即$\mathbf{E}$的结构，如图3：

<MultiModal>![Fig. 3，图中分子以SMILES描述为：O=S(N1CCC2=C1C=CC(C)=C2)(C(F)(F)F)=O](/media/uploads/64bcdf9b-68b4-46f7-ade9-0035e49e9853.png)</MultiModal>

<Checkpoint>[解开桥环结构，消除水形成苯环，$\mathbf{E}$的结构如图3：  <MultiModal>![Fig. 3，图中分子以SMILES描述为：O=S(N1CCC2=C1C=CC(C)=C2)(C(F)(F)F)=O](/media/uploads/64bcdf9b-68b4-46f7-ade9-0035e49e9853.png)</MultiModal>](1)</Checkpoint>

$\mathbf{E}$含有一个六元环和一个五元环，说法1正确。
生成$\mathbf{E}$的过程中经历了图2中间体，含有三个五元环（和一个六元环），说法2正确。生成$\mathbf{E}$为D-A反应，周环机理，说法3错误。

$\mathbf{E}$被氢化铝锂还原，脱去三氟甲磺酰基，得到$\mathbf{F}$，结构如图4：

<MultiModal>![Fig. 4，图中分子以SMILES描述为：CC1=CC2=C(C=C1)NCC2](/media/uploads/497e3917-73ef-4445-b04e-e882d419bbeb.png)</MultiModal>

<Checkpoint>[三氟甲磺酰基被四氢铝锂还原，得到$\mathbf{F}$如图4：  <MultiModal>![Fig. 4，图中分子以SMILES描述为：CC1=CC2=C(C=C1)NCC2](/media/uploads/497e3917-73ef-4445-b04e-e882d419bbeb.png)</MultiModal>](1)</Checkpoint>

$\mathbf{F}$脱去一分子氢气可以形成芳香性吲哚环，说法4正确。