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Articles Archive for April 2007

Still In The RBF »

[26 Apr 2007 | 31 Comments | 9,724 views]

Taber, Sikkander, and Storck. JOC, 2007, ASAP. DOI: 10.1021/jo070257g.
A short synthesis and therefore a short post on the synthesis of this secondary metabolite from Laurencia cartilaginea. The family, bromochamigrenes, show selective, potent cytotoxicity in the NCI 60 cell antitumor, and are thus quite deserving of Douglass Taber’s work (who gave a nice lecture here on Tuesday). The key to the synthesis is the carbene insertion, but let’s look at the retro first:

As you can see, the exciting chemistry is happening at a damn congested neo-pentyl centre, so getting anything to …

Still In The RBF »

[25 Apr 2007 | 22 Comments | 16,376 views]

Nicolaou, Edmonds, Li and Tria. ACIEE, 2006, Early View. DOI: 10.1002/anie.200700586.
First of all – an apology for my sluggish writing. I’ve been on holiday in Zurich (the ETH is gorgeous!), and thus have been out of the loop. As much as I appreciate all the work done on this molecule, I’m sure I’m not the only one who would like to see it have a little rest for a while. However, we can’t do that without one last flourish, again from KCN’s labs. Those of you who read his original …

Still In The RBF »

[14 Apr 2007 | 28 Comments | 19,337 views]

Nicolaou, Tang and Wang. Chem. Comm., 2007, Advance Article. DOI: 10.1039/b704589a.
And again! This second publication (the third is due very soon…) by Nicolaou is another formal synthesis, actually going to the same intermediate that Snider did in the last post. Actually, looking at these two papers, alarm bells started ringing, as the retrosyntheses are not dissimilar:

Now I’m not trying to say that there was any foul-play here – just that this strategy seems quite popular! The interesting bit, I guess, is then the synthesis of that decalin, which thankfully …

Still In The RBF »

[11 Apr 2007 | 16 Comments | 11,291 views]

Snider, Zou, Chen and Taylor. Org. Lett., 2007, ASAP. DOI: 10.1021/ol070563g.
Another publication of this popular beastie, though with less drama than the Nicolaou paper, which I covered back in October. This is a formal synthesis, working towards an intermediate in the afore mentioned paper, using methods I feel are quite old-school, though completed in style. To help figure this one out, I’ve shown the target intermediate as drawn in both papers, with a quick retro on the enone.

The synthesis started quickly, completing the dione in good yield, although as …

Still In The RBF »

[5 Apr 2007 | 30 Comments | 11,118 views]

Maier and Varseev. Org. Lett., 2007, ASAP. DOI: 10.1021/ol070049a.
Although the biological profile of this zwitterionic target is sparse to say the least, it’s thought that it might have an interesting med-chem role, as the parent compound, symbioimine, has a very interesting activity. Even though it is non-toxic at 100 μg levels, it inhibits differentiation of precursor osteoclast cells (RAW264) into mature osteoclasts, and also slightly inhibits COX-2. However, need I say that the architecture is very appealing? Martin Maier did..
Their synthesis hangs on one particularly effective transformation – creation of …

Still In The RBF »

[2 Apr 2007 | 25 Comments | 9,004 views]

Smith and Beshore. JACS, 2007, ASAP. DOI: 10.1021/ja070336+
A deceptively simple looking structure, lyconadin A and the related lyconadin B were the targets of this paper by Amos Smith. The biological profile was somewhat simple, showing moderate cytotoxicity against epidermoid carcinoma KB cells, but the pentacyclic structure is reason enough to interest us, right?

The retosynthesis might not be too revealing, so I guess it’s time to look at the forward – and surprise (!!!) – it’s the cyclisations that I found most interesting. The initial cyclisation precursor was produced from …