<MultiModal>![BrC1=CC(COC/C=C(C)\C)=CC=C1>$LDA$ (1.1eq),$THF$, R.T.>[A], where $LDA$ is lithium diisopropylamide and $THF$ is tetrahydrofuran](/media/uploads/9ff244a2-a630-4a2a-b270-2308c2687424.png)</MultiModal>

Please select the main product A of this reaction
<MultiModal>![BrC1=CC(COC/C=C(C)\C)=CC=C1>$LDA$ (1.1eq),$THF$, R.T.>[A]，其中$LDA$为二异丙基氨基锂，$THF$为四氢呋喃](/media/uploads/9ff244a2-a630-4a2a-b270-2308c2687424.png)</MultiModal>

请选择该反应的主产物A
<MultiModal>![CC(C1COCC2=CC=CC=C21)=C](/media/uploads/4174e285-5b72-4f6b-b28e-e714f7f4d2f1.png)</MultiModal>
<MultiModal>![C/C(C)=C1COCC2=CC=CC=C2/1](/media/uploads/d4f7f230-bbfd-4f1b-9516-59437f4b214b.png)</MultiModal>
<MultiModal>![CC(C)C1=COCC2=CC=CC=C21](/media/uploads/9e447564-4e17-4ee5-a58a-9c73da87ad48.png)</MultiModal>
<MultiModal>![BrC1=CC(CO)=CC=C1](/media/uploads/7202a726-4123-4352-815e-b83ba72a4cf8.png)</MultiModal>
<MultiModal>![BrC1=CC=CC(C(C(C)(C=C)C)O)=C1](/media/uploads/62ab212d-2924-47fe-bfe3-ba7ba8404004.png)</MultiModal>
<MultiModal>![CC1(C)C2=CC=CC=C2COC=C1.C.C](/media/uploads/86180252-9651-4a0d-bfdc-487bfcf8e153.png)</MultiModal>
<MultiModal>![CC(C1COCC2=CC=CC=C21)=C](/media/uploads/4174e285-5b72-4f6b-b28e-e714f7f4d2f1.png)</MultiModal>
<MultiModal>![C/C(C)=C1COCC2=CC=CC=C2/1](/media/uploads/d4f7f230-bbfd-4f1b-9516-59437f4b214b.png)</MultiModal>
<MultiModal>![CC(C)C1=COCC2=CC=CC=C21](/media/uploads/9e447564-4e17-4ee5-a58a-9c73da87ad48.png)</MultiModal>
<MultiModal>![BrC1=CC(CO)=CC=C1](/media/uploads/7202a726-4123-4352-815e-b83ba72a4cf8.png)</MultiModal>
<MultiModal>![BrC1=CC=CC(C(C(C)(C=C)C)O)=C1](/media/uploads/62ab212d-2924-47fe-bfe3-ba7ba8404004.png)</MultiModal>
<MultiModal>![CC1(C)C2=CC=CC=C2COC=C1.C.C](/media/uploads/86180252-9651-4a0d-bfdc-487bfcf8e153.png)</MultiModal>
Benzene rings without strong electron-withdrawing groups are difficult to form benzyne intermediates.

<Checkpoint>[Benzene rings without strong electron-withdrawing groups are difficult to form benzyne intermediates](1)</Checkpoint>

The most acidic site of the substrate is the proton at the benzylic position. Therefore, $LDA$ abstracts the proton at the benzylic position, first forming a carbanion intermediate:

<MultiModal>![BrC1=CC([CH-]OC/C=C(C)\C)=CC=C1](/media/uploads/b67a7bc6-0cee-48ad-a7c8-96811c349170.png)</MultiModal>

<Checkpoint>[$LDA$ abstracts the proton at the benzylic position, first forming a carbanion intermediate](1)</Checkpoint>

Then a one-step [2,3]-Wittig rearrangement occurs to give the final product E.

<Checkpoint>[Then a one-step [2,3]-Wittig rearrangement occurs to give the final product E](1)</Checkpoint>
苯环上没有强吸电子基团作用，难以形成苯炔中间体。

<Checkpoint>[苯环上没有强吸电子基团作用，难以形成苯炔中间体](1)</Checkpoint>

底物酸性最强的位点是苄位上的质子，因此因此$LDA$攫取苄位上的质子，首先形成碳负离子中间体：

<MultiModal>![BrC1=CC([CH-]OC/C=C(C)\C)=CC=C1](/media/uploads/b67a7bc6-0cee-48ad-a7c8-96811c349170.png)</MultiModal>

<Checkpoint>[$LDA$攫取苄位上的质子，首先形成碳负离子中间体](1)</Checkpoint>

接着发生一步[2,3]-Wittig重排得到最终产物E

<Checkpoint>[接着发生一步[2,3]-Wittig重排得到最终产物E](1)</Checkpoint>