[Scatter]

So I'm jealous that the graduate forum gets problems of the week, so I thought I'd post this for undergrads who want to try a synthesis for fun.  This will probably be easy for a lot of people on here, but for people who have only started getting their feet wet with organic synthesis (like me) this one might be somewhat of a challenge.

Enjoy!  

Design a synthesis for the transformation of 1-butyne to 3-octyn-6-ol using 1-butyne as the only source for carbons.  
You can just list the reagents and what's going on in each synthetic step if you want, but bonus points if you post a complete (or as close to complete as you can) arrow pushing mechanism.

[azmanam]

Well done.  Great idea, and good problem.  I won't spoil the fun, but do encourage other undergrads to try the problem.   Lots of fun for all

[Scatter]

Glad to see the problem of the week guru approves.

[nj_bartel]

Cool idea, I might make some of these too if you don't keep up with it

[Scatter]

Neat!  Well, I'm gonna guess that most undergrads on this board usually only want help with homework, but I encourage anyone who even thinks they might be able to do this problem to try it (hints are available).  Doing these will seriously help you in your coursework.  Synthesis problems are already helping me a lot.

[nj_bartel]

Well, I guess I'll give one idea.  Deprotonate the alkyne with sodium amide and SN2 it on the acetal of 1-bromo-2-butanol, hydrolyze the acetal with aqueous acid, then reduce the ketone with borohydride.

[Oxy]

In my opinion:

[wing0714]

Good idea! And here I am to support this wonderful problem~~~

[nj_bartel]

Can't modify my post, misread the problem   Disregard.  I like the last solution.

[Scatter]

Oxy has it.  Though, can H20 alone be used to protonate in the last step?  I had HCl in H20.  I thought H20 alone wouldn't be acidic enough... Someone correct me if I'm wrong on that point, but for all intensive purposes you recognized that the last step is protonation, so congrats.

[nj_bartel]

It would work moderately well to protonate in that manner.  Weak acid or dilute strong acid would probably be better though.

[Oxy]

Oxy has it.  Though, can H20 alone be used to protonate in the last step?  I had HCl in H20.  I thought H20 alone wouldn't be acidic enough... Someone correct me if I'm wrong on that point, but for all intensive purposes you recognized that the last step is protonation, so congrats.

Alcohols have pKa ~15 (ethanol), and H₂O ~14, not a much difference. Alkoxides dissolve well in water, but not the same with most of alcohols. They will seperate into two phases. So I think we can use H₂O only to protonate this alkoxide. At the end, I agree that dilute acid is better .