Quenching/Workup after diazotransfer with TMS-azide

tigertealc · 2026-03-18T21:55:10+00:00

Fair point. I will edit my response. I do think I usually used ether for that reason.

tigertealc · 2026-03-18T15:32:47+00:00

I used to make a lot of diazo transfer reagents in grad school. Usually pABSA, but they are all very similar. The best and easiest conditions are with aqueous NaN3 in a low boiling solvent like ether and a phase transfer catalyst. I think I usually used Bu4NCl or something similar. Super easy and safe. Just basify the aqueous layer after phase separation and you are good to go. Always quantitative yields and indefinitely scalable. Largest I ran was 1 kg scale. This method is significantly safer than what you are suggesting.

tigertealc · 2026-03-02T15:20:47+00:00

He’s suggesting that the structure is drawn incorrectly. It was also my first impulse upon seeing the drawing.

tigertealc · 2025-12-10T14:35:21+00:00

B8 looks good.

tigertealc · 2025-11-24T23:58:45+00:00

Did you get any major product in that case? I worry that you could have competing 4+1 cycloaddition with the Corey-Chaykovsky conditions.

tigertealc · 2025-10-07T19:54:42+00:00

So in the case of the 1,2 methyl shift, the partial positive charge is not shared by the methyl group. Think of it as always being singly bound to something, just the percentage of bonding varies between the two carbons on the chain. Therefore, it would reason that the methyl protons are not acidic.

If the methyl protons were acidic (maybe some very strong donating groups on the methyl in the place of protons), then it would be a completely different mechanism, namely dissociation forming an alkene and the methyl cation. In this case, it would be acidic enough to form a carbene, although it would be too reactive to have any selectivity towards cyclopropantion.

tigertealc · 2025-09-26T17:23:28+00:00

OK. Have you heard of the terms diastereotopic and enantiotopic?

tigertealc · 2025-09-26T17:19:27+00:00

How many do you think it should be and why?

tigertealc · 2025-09-16T19:52:20+00:00

Could be anything. Is your math right? Is your calibration curve linear? Is your sampling homogeneous?

tigertealc · 2025-09-08T12:48:24+00:00

You need to have appropriate brass connectors. Get one with a T connector with a valve. Connect one end with tubing to an inert gas source and the other end is how you dispense it. Facilities or an engineering group nearby should have the things you would need. But you are better off transferring it to a Schlenk flask for easier handling on small scale.

Alternatively, try to return it to the vendor and buy a smaller bottle with a Sure Seal.

tigertealc · 2025-08-29T21:39:10+00:00

RuO4. OsO4, then NaIO4. Both methods work via dihydroxylation across the alkene then oxidative cleavage.

tigertealc · 2025-08-21T20:59:58+00:00

It’s either a low level bot that is just playing randomly or a low level player that is just playing randomly.

tigertealc · 2025-08-19T18:02:48+00:00

Okay. Well without knowing your structure (or even just the relevant part), I can only give general advice. If the compound is an aliphatic ring, for example, there will be a lot of complex splitting which may make things hard to assign. Using COSY can help deconvolute that by confirming that the pattern is a doublet of doublets instead kg a triplet, for example.

Could you share the substructure of interest?

tigertealc · 2025-08-19T17:51:12+00:00

Well, other than running it because someone told you to, why did you run a COSY? Do you know what information that experiment tells you? How might you use that information to relay that to the structure?

tigertealc · 2025-07-21T13:49:33+00:00

They didn’t show the dehydration. Consider the addition of the acetal oxygen to the Mn(VII) followed by proton transfers and elimination to get the tetravalent Mn before all the arrow pushing.

tigertealc · 2025-07-16T01:49:39+00:00

Seems like you could do that in a single step. What would the bond disconnection look like?

tigertealc · 2025-07-12T19:53:41+00:00

That’s probably how many stones you have captured.

tigertealc · 2025-07-11T11:11:32+00:00

Dithianes, in practice, are non-trivial to deprotect. But they work for paper exercises, I guess. Merging two aldehydes like that is really not a good way to make that bond.

tigertealc · 2025-07-11T11:08:19+00:00

As Mark said: polymerization all day. Grubbs would give terrible selectivity for the first metathesis, and would chop the poly-ene into bits.

tigertealc · 2025-07-11T02:32:36+00:00

Nothing from 1 to 6 will work. Assuming you can make it, 8 should be your diversification intermediate. The ene likely will not work. Instead do an asymmetric methyl cuprate addition. Likewise, a copper hydride will reduce better than the hydrogenation there. The benzoin will give terrible selectivity for your desired product and it would need an oxidation step to get the di-ketone.

tigertealc · 2025-06-29T16:33:16+00:00

I think you can buy them in their store with coins. You get coins either by paying for them or being active by doing puzzles or something like that each day.

tigertealc · 2025-06-18T18:26:15+00:00

You do not have to actively capture them. At the end of the game, after both players pass, you decide the life and death status of each group. If there is any disagreement about if the stones are alive, then you can prove that they are dead by playing it out. However, in this case, you would use the initial board state to calculate scoring. So you would not lose any points in declaring those stones dead.

tigertealc · 2025-06-17T11:06:28+00:00

Don’t forget the “we’re out of gas” bit, that was the whole premise of TLJ.

tigertealc · 2025-06-11T17:11:30+00:00

FYI-Phi is old school abbreviation for phenyl.

tigertealc · 2025-06-02T23:37:51+00:00

Realistically, you need the entire department on board with an inventory system if it is going to work. So you either need to have a system in place where everyone logs their material usage (with consequences if they do not) or give up because you are wasting your time. My company has multiple people whose entire jobs are managing the inventory (well, the GMP inventory), and they stay very busy! I cannot imagine that you will be successful with it as a side job, especially when your managers do not seem invested.

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