Synthesis of 3-Methylenecyclopentene from 1-methylCyclobutene [closed]








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How do I make 3-Methylenecyclopentene 


[![enter image description here](https://i.stack.imgur.com/U8FjE.jpg)](https://i.stack.imgur.com/U8FjE.jpg)


from 1-methylcyclobutene?


[![enter image description here](https://i.stack.imgur.com/pOraO.jpg)](https://i.stack.imgur.com/pOraO.jpg)


I thought to do ring opening reaction to add 1 carbon atoms but this won't add double bond in product. How to start please?




Here is my try.


1. Ozonolysis
2. Aldol condensation using a hindered base (like LDA)
3. Wittig reagent to convert $\ce{C=O}$ to $\ce{C=C}$


**Step 1:**


[![enter image description here](https://i.stack.imgur.com/dMrWc.png)](https://i.stack.imgur.com/dMrWc.png)


**Step 2:**


I used $\ce{LDA}$ which abstracts a proton from the least hindered carbon near to a carbonyl group. (So that the resulting carbanion is stable).
I am not drawing the enolate ion formation etc. You can find the reaction mechanism for aldol condensation [here](https://en.wikipedia.org/wiki/Aldol_condensation) and the reaction using $\ce{LDA}$ [here](http://www.masterorganicchemistry.com/2011/08/05/reagent-friday-lithium-di-isopropyl-amide-lda/).
[![enter image description here](https://i.stack.imgur.com/gbbb6.png)](https://i.stack.imgur.com/gbbb6.png)


[![enter image description here](https://i.stack.imgur.com/NwgOm.png)](https://i.stack.imgur.com/NwgOm.png)


After protonation, you can heat the compound to remove $\ce{OH-}$ which is a simple dehydation. There are two possible alkenes. One of them (the one given below) is more stable because of conjugation.


[![enter image description here](https://i.stack.imgur.com/2jTYq.png)](https://i.stack.imgur.com/2jTYq.png)


**Step 3:**


We are almost done. To replace $\ce{C=O}$ with $\ce{C=C}$, use [wittig reagent](https://en.wikipedia.org/wiki/Wittig_reaction).


[![enter image description here](https://i.stack.imgur.com/64KWX.png)](https://i.stack.imgur.com/64KWX.png)


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