A methanol solution of the following substrate transforms into a tricyclic compound under light irradiation; the reaction successively goes through two intermediates $\bf{A}$ and $\bf{B}$.

<MultiModal>![`C=CCOCOC1=CC=CC=C1C(=O)OC` in methanol, irradiated with light of wavelength 300nm, yields `[H][C@@]12C=C[C@]13[C@@](CC(C(OC)=O)=C2)(COCO3)[H]`](/media/uploads/f67affc2-7ff5-41be-a3e0-8b8d0b4cdfe9.png)</MultiModal>

Select the correct option from the following options.
以下底物的甲醇溶液在光照下会转化为一种三环化合物；该反应先后历经两个中间体$\bf{A}$和$\bf{B}$。

<MultiModal>![`C=CCOCOC1=CC=CC=C1C(=O)OC`在甲醇中接受波长为300nm的光照，生成`[H][C@@]12C=C[C@]13[C@@](CC(C(OC)=O)=C2)(COCO3)[H]`](/media/uploads/f67affc2-7ff5-41be-a3e0-8b8d0b4cdfe9.png)</MultiModal>

选出下列选项中正确的一项
All other options are incorrect
$\bf{B}$ has 3 rings
$\bf{A}$ has two rings
$\bf{A}$ exhibits aromaticity
$\bf{B}$ contains three conjugated carbon-carbon double bonds.
$\bf{A}$ does not contain highly strained ring systems.
其他选项均不正确
$\bf{B}$具有3个环
$\bf{A}$具有两个环
$\bf{A}$具有芳香性
$\bf{B}$中具有三个共轭的碳碳双键
$\bf{A}$中不存在高张力环系
The reaction occurring under illumination is an electrocyclic reaction. The double bond in the starting material can react with the benzene ring, but the resulting product is difficult to determine. First, deduce the structure of $\bf{B}$ from the product. It is not difficult to find that the four-membered ring in the product should be produced under illumination. Break the corresponding bond to obtain $\bf{B}$: `O=C(OC)/C1=C/C=C\C=C2OCOCC\2C1`. $\bf{B}$ has only one eight-membered ring and one six-membered ring.

<Checkpoint>[The structure of $\bf{B}$ is `O=C(OC)/C1=C/C=C\C=C2OCOCC\2C1`, and it has two rings. Option B is incorrect.] (1)</Checkpoint>

The eight-membered ring of $\bf{B}$ has three conjugated carbon-carbon double bonds.

<Checkpoint>[$\bf{B}$ has three conjugated carbon-carbon double bonds. Option E is correct.] (1)</Checkpoint>

The large ring system in $\bf{B}$ should be obtained by the ring-opening of $\bf{A}$. Deduce from $\bf{B}$, $\bf{A}$ may have the following structures:

<MultiModal>![$\bf{A1}$：`O=C(OC)C12CC3COCOC31C=CC=C2`；$\bf{A2}$：`O=C(OC)C12CC3COCOC3=CC1C=C2`](/media/uploads/e491b594-72ec-450a-ad72-719043b532c7.png)</MultiModal>

Only $\bf{A1}$ can be produced from the starting material. Therefore, the structure of $\bf{A}$ is `O=C(OC)C12CC3COCOC31C=CC=C2`, which does not have an aromatic ring.

<Checkpoint>[The structure of $\bf{A}$ is `O=C(OC)C12CC3COCOC31C=CC=C2`, which does not have an aromatic ring. Option D is incorrect.] (1)</Checkpoint>

$\bf{A}$ has 1 four-membered ring and two six-membered rings, a total of 3 rings.

<Checkpoint>[$\bf{A}$ has 1 four-membered ring and two six-membered rings, a total of 3 rings and has a highly strained ring system. Options C and F are incorrect.] (1)</Checkpoint>

Choose E.

<MultiModal>![Structure of $\bf{B}$: `O=C(OC)/C1=C/C=C\C=C2OCOCC\2C1`](/media/uploads/91848ad4-c1c2-4405-bfac-d645658c475a.png)</MultiModal>
在光照下发生的反应为电环化反应，原料中的双键可以与苯环发生反应，但生成的产物难以确定。先从产物推断$\bf{B}$的结构，不难发现产物中的四元环应为光照条件产生的，将相应的键断开，得到$\bf{B}$：`O=C(OC)/C1=C/C=C\C=C2OCOCC\2C1`。$\bf{B}$仅有一个八元环和一个六元环

<Checkpoint>[$\bf{B}$的结构为`O=C(OC)/C1=C/C=C\C=C2OCOCC\2C1`，有两个环，选项B错误](1)</Checkpoint>

$\bf{B}$的八元环中有三个共轭的碳碳双键

<Checkpoint>[$\bf{B}$中具有三个共轭的碳碳双键，选项E正确](1)</Checkpoint>

$\bf{B}$中的大环体系应为$\bf{A}$开环所得。由$\bf{B}$倒推，$\bf{A}$可能有以下几种结构：

<MultiModal>![$\bf{A1}$：`O=C(OC)C12CC3COCOC31C=CC=C2`；$\bf{A2}$：`O=C(OC)C12CC3COCOC3=CC1C=C2`](/media/uploads/e491b594-72ec-450a-ad72-719043b532c7.png)</MultiModal>

其中仅有$\bf{A1}$可由原料产生，因此$\bf{A}$的结构为`O=C(OC)C12CC3COCOC31C=CC=C2`，其中不具有芳香环

<Checkpoint>[$\bf{A}$的结构为`O=C(OC)C12CC3COCOC31C=CC=C2`，其中不具有芳香环，选项D错误](1)</Checkpoint>

$\bf{A}$中具有1个四元环和两个六元环，共3个环

<Checkpoint>[$\bf{A}$中具有1个四元环和两个六元环，共3个环且有高张力环系，选项C、F错误](1)</Checkpoint>

选E

<MultiModal>![$\bf{B}$的结构为`O=C(OC)/C1=C/C=C\C=C2OCOCC\2C1`](/media/uploads/91848ad4-c1c2-4405-bfac-d645658c475a.png)</MultiModal>