Decent references for SN2 displacement of tosylate with acetylide

In summary, the speaker is struggling to find reliable sources for lithiating a terminal alkyne and reacting it with a tosylate. They attempted a procedure with THF, nBuLi, and tosylated phenylethanol at -78 degrees, but it did not work. Even though there was a color change, the NMR and TLC results showed a mixture of starting materials. The speaker suggests that adding ethylenediamine or TMEDA may be necessary, but ultimately solved the issue by adding 20% v/v DMSO and warming after adding the tosylate.
  • #1
burningbend
31
0
i'm having trouble finding good references for lithiating a terminal alkyne and reacting that acetylide with a tosylate, and my goto procedure didn't work. can anyone give me a hand?

procedure i did try:

alkyne in THF at -78
1.0 eq nBuLi added
1.0 eq tosylated phenylethanol added (color change here) still at -78
ammonium chloride workup

despite the color change, the NMR and TLC just show a mixture of starting materials and I'm a bit baffled as to why our normal run-through didn't succeed. maybe adding ethylenediamine or TMEDA is necessary?
 
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  • #2
meh, pretty sure i fixed it by adding 20% v/v DMSO and warming after adding the tosylate.
 

1. What is an SN2 displacement reaction?

An SN2 displacement reaction is a type of nucleophilic substitution reaction in which a nucleophile attacks a carbon atom that is attached to a leaving group, causing the leaving group to leave and form a new bond with the nucleophile. This reaction follows a second-order kinetics, hence the name SN2 (substitution-nucleophilic-bimolecular).

2. What is a tosylate?

Tosylate, also known as tosyl or TsO, is a functional group that consists of a sulfonate group attached to a toluene ring. It is commonly used as a leaving group in organic reactions due to its stability and ability to be easily displaced by nucleophiles.

3. What is an acetylide?

An acetylide is a negatively charged ion that contains a carbon-carbon triple bond. It is often used as a nucleophile in organic reactions due to its high reactivity and ability to form new carbon-carbon bonds.

4. How does SN2 displacement of tosylate with acetylide occur?

In SN2 displacement of tosylate with acetylide, the acetylide acts as the nucleophile and attacks the carbon atom attached to the tosylate group. This causes the tosylate group to leave, forming a new carbon-carbon bond between the acetylide and the carbon atom. The resulting product is an alkyne.

5. What are some decent references for SN2 displacement of tosylate with acetylide?

Some decent references for SN2 displacement of tosylate with acetylide include academic textbooks on organic chemistry, scientific journals such as the Journal of Organic Chemistry, and online resources such as ChemSpider and Reaxys. It is important to always cross-check information from multiple sources to ensure accuracy.

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