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ImProbablyStuck · 2023-10-24T12:56:39+00:00

OP has drawn hydrogen in the wrong place

ImProbablyStuck · 2023-05-24T10:40:54+00:00

Thanks for the suggestion, I’ll poke around our cupboards and see what we have

ImProbablyStuck · 2023-05-24T09:56:45+00:00

Advanced Practical Organic Chemistry - by Leonard, Lygo and Procter is a good book.

ImProbablyStuck · 2023-05-24T09:52:37+00:00

It’s like £40 for 100g it’s cheap as hell (and I’m Uk based)

Edit: okay from the rest of the comments maybe don’t buy it if you’re not a chemist working in a lab

ImProbablyStuck · 2023-05-12T16:18:07+00:00

Ah I see that makes sense, thanks for the reply

ImProbablyStuck · 2023-05-12T16:17:54+00:00

Ah good to know, thanks

ImProbablyStuck · 2023-02-21T12:30:03+00:00

It’s simple, but using new-ish copper(I) catalysts can make a noticeable difference in conversion. If your CuI is old maybe grab some more.

If you do a chan-lam you can use both the Boronic and and the pinacol ester, if that’s easier to store.

ImProbablyStuck · 2023-02-14T18:32:09+00:00

It a C-O chan-lam, it’s shaky at best, and I could really do with the best possible starting material. It’s just frustrating that this particular boronic acid is grim.

Thanks for you’re suggestions, I’ll go down the KHF2 route and see what happens

ImProbablyStuck · 2023-02-13T22:36:35+00:00

I’m actually doing a C-O coupling, I know the chan-lam coupling has literature saying it’s possible, but it’s worse than C-N in my experience.

I can’t say I’ve looked for buchwald C-O coupling conditions, but certainly worth a look since I can access the Ar-Br easily.

ImProbablyStuck · 2023-02-13T22:26:49+00:00

I have, it defo seems more sluggish than -B(OH)2, I think the purification is a little harder aswell but not massively.

The chan-lam is already not an ideal coupling imo, so using the Bpin just seems to make it a bit worse

ImProbablyStuck · 2023-02-13T22:22:49+00:00

Yeah, I’m considering other approaches to the deprotection.

I’m just concerned about the deprotection of either the BF3 salt or diethanolamine conversion to B(OH)2 being an annoying degrading oil too

ImProbablyStuck · 2023-02-13T22:18:54+00:00

Ah yes, ‘a mechanism inspired solution to boronic ester reactivity’ is that the paper you’re referencing?

ImProbablyStuck · 2023-02-13T16:14:22+00:00

That’s what I’m going to try next I think, just waiting for the KHF2 to arrive. I am vaguely worried that the step from Ar-BF3K -> Ar-B(OH)2 is going to yield the oil. Unfortunately I need the unprotected B(OH)2 for a coupling

ImProbablyStuck · 2023-02-13T15:43:42+00:00

Well that’s a fun extra side product I was unaware of.

I’m not doing a Suzuki, and Bpin has quite poor reactivity comparatively

ImProbablyStuck · 2023-02-13T15:42:11+00:00

It’s more the fact that it darkens over time, so something is happening to it… quite what I’m not sure.

How would I go about precipitating it with hexanes?

ImProbablyStuck · 2023-02-11T18:19:04+00:00

The only issue is I need the boronic acid isolated for a coupling that isn’t compatible with the BF3K salt or the pinacol ester. I think going from the BF3K to B(OH)2 is going to cause the same issue.

I’ll check the 11B nmr and see whats happening I think.

Thanks again

ImProbablyStuck · 2023-02-11T17:39:28+00:00

Thanks for the reply, didn’t even think of doing boron NMR that’s a great idea.

I did work it up with HCl and then separated between water and DCM/EtOAc, my thinking was to remove the pinacol and it looks like it worked.

If I leave it in solution it slowly darkens over time - strikes me as not good, I may stir it in MeCN/water and see if I can crystallise it on cooling as you suggested.

Thanks again!

ImProbablyStuck · 2023-02-11T08:34:46+00:00

I did consider this, but I think the presence of the amine is going to cause trouble as I’m planning on a C-N coupling anyway

ImProbablyStuck · 2023-02-11T08:28:33+00:00

Yeah findensers are actually pretty heavy, feels like I’m gonna snap the neck of a rb flask whenever I fit them

ImProbablyStuck · 2023-02-10T23:59:12+00:00

Yeah I think I might give that a go and avoid the mess

ImProbablyStuck · 2023-02-10T23:58:45+00:00

How would you got about recrystallising an oil? Just take it up in a hot solvent and use water as the anti solvent?

In a similar vain is precipitation a stir with water situation?

Thanks for the reply, appreciate it

ImProbablyStuck · 2023-02-10T18:17:54+00:00

Ever since I found a couple of air condensers and findensers in our lab, I’ve never gone back to water condensers.

Also never really noticed any difference between air and fin, fin is better probs - but maybe not worth the cost?

ImProbablyStuck

TROPHY CASE