[Messi]

Essentially yes. These procedures are published, just check the literature.

Yup, I got it! http://www.orgsyn.org/orgsyn/orgsyn/prepcontent.asp?prep=cv2p0358#Note169N2

The free-base form of this compound is probably fairly unstable so I would isolate it as a salt and generate the free base for in situ in the next step.

Yup, I understand this. Thing is, wouldn't I want to run a column on my product after I brominate it before I do the next reaction?

[discodermolide]

Did the reduction work?

[Messi]

Well I just took my NMR and all I saw was my NMR solvent chloroform. It seemed as if my reduction product wasn't very soluble in chloroform at all... I'm not sure if its my reaction that didn't work or if it was poor selection of solvent.. that yielded poor NMR result..

[discodermolide]

Try methanol for the NMR. But you did isolate something?

[Messi]

Ill try ethanol when I'm back in the lab after my snack break.

Yes, I definitely isolated something. I see a yellow/red oil with a proline like smell to it.

[discodermolide]

You need a deuterated solvent for the H-NMR

[Messi]

You need a deuterated solvent for the H-NMR

Yup! By the way, do you agree with me that it is indeed odd that my product isn't soluble with chloroform and isn't showing up in the NMR?

[discodermolide]

It is quite a polar molecule so it is not surprising that it may not be chloroform soluble.
What does the TLC look like?

[Messi]

Didn't take a TLC. Wasn't sure what eluent system I should use

Took my HNMR in deuterated methanol, thumbs up! Successful reaction! Now to add my bromine tonight

[Messi]

I found this procedure:

A mixture of (S)-amino alcohols 5 (0.15 mol) dissolved in 20% HBr aqueous solution (130 mL) was concentrated to dryness under reduced pressure. Owing to complete removal of water, the residue was dissolved in hot EtOH (40 mL) and the solvent was evaporated in vacuum to give amino alcohol hydrobromides. The obtained hydrobromide salts were then mixed with PBr3 (25.44 g, 0.093 mol) and refluxed for 10 min. After cooling, an excess of PBr3 was then removed by washing the mixture with Et2O several times and the residue was recrystallized from i-PrOH to afford 6a–e (over 86% yields).

I am trying to translate this procedure to layman terms. Does the above procedure translate to:

1) Dissolve amino alcohol in an HBr solution in an RBF
2) Add hot EtOH to RBF (Any reason why hot?)
3) Throw mixture on rotavap (How long?)
4) Add PBr₃ to RBF and reflux for ten minutes
5) Throw RBF contents in a buchner funnel and aspirate via vacuum filtration
6) Collect crystal/salts and undergo next step in my reaction (Purification not necessary?)

[discodermolide]

Well you are not really a layman anymore, not after doing a LiAlH₄ reaction
The procedure tells you exactly what to do.
The solution of the amino alcohol in HBr/water was evaporated to dryness, then hot ethanol was added. The re-evaporated in vacuum. This is to remove all traces of water before adding PBr₃. Ethanol and water form an azeotrope.
You evaporate until it is dry.
After the reaction with PBr₃ you then cool and add ether and filter, wash the solid with ether several times. This removes excess PBr₃.
You then dissolve that residue in iso-propanol and crystallise the product. This is the purification step.

[Messi]

Well you are not really a layman anymore, not after doing a LiAlH₄ reaction

I beg to differ I still have a lot of learning to do! I have been doing a lot of searches on SciFinder to try learn quickly and efficiently!

Ethanol and water form an azeotrope.

Now I understand! This is ingenious! Awesome!

After the reaction with PBr₃ you then cool and add ether and filter, wash the solid with ether several times. This removes excess PBr₃.

When you say filter here, do you mean vacuum filtration or gravity filtration?

You then dissolve that residue in iso-propanol and crystallise the product. This is the purification step.

Easy enough, add my solid/salt to a warm solution of iso-propanol then let it cool. I will then add this cooled solution (hopefully I see crystals in my E-flask) to a Buchner funnel and purify it via vacuum filtration!

Side note: I plan on reacting this amine with another compound after. Do you recommend I do this reaction in situ? Also, I need the amine in its free base form when I do the reaction, so all I do is react the salt with NaOH then do my reaction?

[discodermolide]

You usually use vacuum filtration.
For the next step: Now I don't know what it is.
But the free amine and the bromomethyl groups are not compatible.
So it may be worth thinking about mixing your next reactant with the HBr amine salt and then add a base such as triethylamine.

[Messi]

You usually use vacuum filtration.

Ok, nice, thanks!

For the next step: Now I don't know what it is.
But the free amine and the bromomethyl groups are not compatible.
So it may be worth thinking about mixing your next reactant with the HBr amine salt and then add a base such as triethylamine.

My reaction is where I react a thioketene with my amine. R₂C=C=S + NHR₂ This will create a thioamide. However, I need my amine in free-base form. Can I throw in my amine + base with my thioketene with the hope that the amine will undergo free base transformation and react with the thioketene? Thing is, I also use TFA for a proton source whenever I add my amine to my thioketene. I am skeptical of using triethylamine in this case because it might add to my thioketene.

[discodermolide]

Do you generate the thioketene in situ, from what?
If it has a precursor then you mix them together and add a base such as triethylamine or Hünig's base.
Triethylamine should not add to the thioketene.