Comments on: Axinellamines

By: » Blog Archive » Publications-Junichiro Yamaguchi-[Itami Organic Chemistry Laboratory, Nagoya University]

Fri, 15 Jan 2010 18:11:18 +0000

[...] DOI: 10.1002/anie.200801138 Selected as VIP paper and Inside Cover in Angew. Chem. Int. Ed. Highlighted in Tot. Syn. Dot Com [...]

By: TotallySynthetic.com » Blog Archive » Palau’amine

TotallySynthetic.com » Blog Archive » Palau’amine — Wed, 30 Dec 2009 18:51:38 +0000

[...] starting point to the chemistry should be familiar to regular readers – hark back to Baran’s 2007 synthesis of the axinellamines, and a familiar intermediate crops up. Using very similar chemistry to that used in the earlier [...]

By: Finally…Total Synthesis:NOS Day 4 at C&ENtral Science

Finally…Total Synthesis:NOS Day 4 at C&ENtral Science — Fri, 12 Jun 2009 18:30:08 +0000

[...] up was Baran. He had a theme in mind (chemoselectivity in syntheses) and he used examples from several molecules his team has tackled to drive that point home. I won’t go into all the stories he [...]

By: Jose

Jose — Mon, 05 May 2008 16:46:53 +0000

Looks like Phil and co. have more work to do!

ASAP Org. Lett., ASAP Article, 10.1021/ol8003904

Nagelamides K and L, Dimeric Bromopyrrole Alkaloids from Sponge Agelas Species

By: HPCC

HPCC — Thu, 17 Apr 2008 07:20:20 +0000

During my Ph. D. I coined the term “invisible yield” for something that you can’t see at all in your flask, typically a droplet of clear colourless oil, but which still shows NMR signals when you add CDCl3 to it and drop it in a probe! Invisible yield is usually 3 mg or less…

By: HPCC

HPCC — Thu, 17 Apr 2008 07:20:07 +0000

By: antiaromatic

antiaromatic — Wed, 16 Apr 2008 23:02:18 +0000

The slice method works okay, but all too often, you end up cutting out parts that don’t belong, especially when you have compounds that don’t stain all that well in the first place.

Also, eventhough it doesn’t make a real difference, I’ve just always felt better about working on 2 mg scale when the compounds were solids. Something about being able to see it in your flask makes you feel a little better…

By: Tot. Syn.

Tot. Syn. — Wed, 16 Apr 2008 22:00:59 +0000

Radical: ‘Need’ is such a strong word… you can still stain a small slice of the prep plate and go with that…

By: Radical

Radical — Wed, 16 Apr 2008 21:07:27 +0000

2 mg reactions can be very useful when the amount of material is limited. One can get a good amount of information out as long as there are no more than two or three major products. Purifying these reactions on preparative TLC is probably the best thing to do, although you do need uv-active compounds for this to work. Of course, the accuracy of the yield is always a concern on such a small scale.

As strange as it may sound, I really prefer working on the 5-10 mg scale to the 20 mg or larger scale.

By: TheEdge

TheEdge — Wed, 16 Apr 2008 20:24:07 +0000

“can some one explain me how can someone work with 2 mg?”

I think it depends a lot on your molecular weight. If you have 2 mg’s and 30 TBS groups, you probably run a lot of reaction at reasonably high dilution with a large excess of reagents, and you still need a good microsyringe. If you have 2mg’s and the compound above, you can probably run things in a microvessel with a reasonable number of equiv. You make a lot of stock solutions. You try things that don’t need extensive workups, and you give up your sep funnels for a pipette and a steady hand.
You purify things on pipette columns or on the HPLC (where you don’t lose anything to your TLC-ing). You mass things in as small a flask or vial as possible so that the value you get is (more) significant. You rely more on mass-spec to figure out what’s going on (because it requires so little material).

It’s not something people really enjoy, but it does feel empowering to be able to do it.