[AlphaScent]

Hello All,

I have a synthesis before me of a compound that would involve a double skipped,  non-conjugated alkyne.

After a coupling reaction I would be left with a triple bond at the 10 and 14 carbon of a hexadecdiyn-1-othp compound.  Would you all think that I could reduce with lithum in liquid ammonia or would the conditions be too harsh and cause isomerization to a conjugated 10,12 alkene system?  I am worried about this happening.  Thank you in advance!!

Cheers!!

[camptzak]

for what its worth, I don't think it will happen. I cant see a way that the shift could take place. let me know how it goes.

[orgopete]

for what its worth, I don't think it will happen. I cant see a way that the shift could take place. let me know how it goes.

I'm of a different opinion. I think potentially, the reaction fails because the CH2 will be more acidic and subject to deprotonation. If this happens, I don't think it can deprotonate ammonia (I could be wrong), so this conjugated anion will resist accepting electrons. Because acetylenes can isomerize to allenes by deprotonation, I think two acetylenes increase that possibility.

I'd try the hydroboration route to get a trans alkene from an acetylene.

We'll see what others think.

[AlphaScent]

I am aware of hydroboration of terminal alkynes to aldehydes, but am unaware of a reduction alkynes to trans alkenes under these conditions.  Attached is what I am trying to accomplish.  See what you think if I were to reduce the first alkyne to a trans alkene first and then alkylate.