Decent references for SN2 displacement of tosylate with acetylide

Click For Summary
SUMMARY

The forum discussion focuses on the challenges of performing SN2 displacement of tosylate with acetylide derived from terminal alkynes. The user attempted a procedure involving lithiating a terminal alkyne in THF at -78°C using 1.0 eq of nBuLi, followed by the addition of 1.0 eq of tosylated phenylethanol. Despite observing a color change, the reaction yielded a mixture of starting materials as confirmed by NMR and TLC. The user resolved the issue by incorporating 20% v/v DMSO and warming the reaction mixture after the tosylate addition.

PREREQUISITES
  • Understanding of SN2 reaction mechanisms
  • Familiarity with lithiating agents such as nBuLi
  • Knowledge of tosylate chemistry
  • Experience with NMR and TLC for reaction monitoring
NEXT STEPS
  • Research the role of DMSO in SN2 reactions
  • Learn about the effects of temperature on reaction kinetics
  • Investigate the use of ethylenediamine and TMEDA as additives in nucleophilic substitutions
  • Explore alternative methods for lithiating terminal alkynes
USEFUL FOR

Chemists, particularly organic chemists and synthetic chemists, who are involved in reaction optimization and troubleshooting in nucleophilic substitution reactions.

burningbend
Messages
31
Reaction score
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?
 
Chemistry news on Phys.org
meh, pretty sure i fixed it by adding 20% v/v DMSO and warming after adding the tosylate.