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Articles Archive for April 2008

Still In The RBF »

[29 Apr 2008 | 33 Comments | 13,436 views]

Dake and Kozak. ACIEE, 2008, EarlyView. DOI: 10.1002/anie.200800522.
A complex little target, this natural product is related to fawcettimine, which we looked at last year. However, fawcettidine has attracted far less synthetic attention than the latter, and this synthesis constitutes the first. Like it’s cousin, drawing a retrosynthesis onto the structure is quite tricky with such tight constraints, so we’ll go straight into the forward synthesis.
The key reaction, developed from some of the groups methodology (in this Org. Lett.), was a palladium mediated enamide annulation. …

Still In The RBF »

[25 Apr 2008 | 9 Comments | 5,831 views]

Lee, Kim, Jang, Choi and Chung. ACIEE, 2008, EarlyView. DOI: 10.1002/anie.200800568.
Antibiotic… blah blah… Merck… Nicolaou… other synthesis covered…
Yep, you all know about platensimycin, and half of you have probably worked on / are working on syntheses of this ‘popular’ target. Eun Lee hasn’t bothered with a full total synthesis, instead satisfying a neat formal of the right-hand ‘cage’ motif. Key to this was the optimisation of a substrate for a rhodium catalysed carbonyl-ylide cycloaddition.
They suggest that they knew that a terminal olefin would have …

Still In The RBF »

[20 Apr 2008 | 29 Comments | 9,037 views]

Toste, Radosevich, Chan and Shih, ACIEE, 2008, EarlyView. DOI: 10.1002/anie.200800554.
Another paper from the Toste group that doesn’t use recycled Rolex watches in any of the steps. Indeed, the metal of choice today is vandadium – read-up on the methodology in this tasty JACS from 2005. Anyway, the target is octalactin A, a medium ring lactone with a bit of murine melanoma and colon tumor busting activity. Previous syntheses by Buszek, Clardy, Shiina and my boss with Andy Holmes, so it’s certainly seen …

Still In The RBF »

[16 Apr 2008 | 43 Comments | 13,178 views]

Roulland, ACIEE, 2008, EarlyView. DOI: 10.1002/anie.200800585.
Yep, just one name. And an impressive synthesis for just one chap (and I don’t think he even had the backing of “Bioic Bros. GMBH” like La Clair). Even the target has more names – this one was independantly isolated three times, gaining haterumalide NA and FR177391as alternative monikers (albeit with different optical rotations…). No mention is made of its biological profile in this paper, but a synthesis of the methyl ester by Snider in 2003 states “Haterumalide …

Still In The RBF »

[13 Apr 2008 | 29 Comments | 23,565 views]

Trost and Zhang, ACIEE, 2008, EarlyView. DOI: 10.1002/anie.200800282.
We’ve looked at two previous syntheses of tamiflu before, those of Corey and Shibasaki, so you’re probably used to me stretching the definition of “natural-product total synthesis” to include it. Stretching the definition to breaking point, actually, but never mind, it’s got a very natural-product look to it (which must lend a little to it’s popularity). The other reason for it’s popularity is that apparently chickens and turkeys are still getting a spot of the sniffles occasionally, so …

Still In The RBF »

[10 Apr 2008 | 9 Comments | 8,436 views]

Aube, Frankowski, Golden, Zeng and Lei. JACS, 2008, ASAP. DOI: 10.1021/ja800574m.
A short and concise synthesis of three members of the stemona alkaloid family by Jeffrey Aube’s group in Kansas. If you’re unaware of this class of natural products, this paper is an excellent place to start, as Aubé goes through the key disconnnection and step in the syntheses of Hart, Morimoto and Padwa. The biological activity of these little beasts is a bit of a mixed bag – to quote “insecticidal, anthelmintic, antitussive, and various neurochemical …

Still In The RBF »

[6 Apr 2008 | 26 Comments | 12,612 views]

MacMillan, Carpenter, Northrup, Chung, Wiener and Kim, ACIEE, 2008, EarlyView. DOI: 10.1002/anie.200800086.
Macrolide time again, and as this is David MacMillan, proline time too. The callipeltoside family of natural products has been reasonably popular, with syntheses from the usual suspects: Trost, Evans, Paterson, and Panek. However, all of those syntheses were of callipeltoside A, so this synthesis marks the first of callipeltoside C, including a reassignment of stereochemistry (the sugar fragment needed all is stereocenters inverted). Retro:

So far reasonably predictable/sensible disconnection – and you’ll note no …

Still In The RBF »

[3 Apr 2008 | 14 Comments | 10,469 views]

Qin, Shen and Zhang, ACIEE, 2008, EarlyView. DOI: 10.1002/anie.200800566.
Second showing in as many months for this popular alkaloid, this route from Yong Qin at the “Department of Chemistry of Medicinal Natural Products and, Key Laboratory of Drug Targeting, West China School of Pharmacy” (can’t get the website to work…) shows a few similarities to the recently covered route by Larry Overman, along with some interesting alternatives. Eschewing Overman’s ambitious palladium cascade designs, they went a bit old-school, planning a carbene insertion into an indole. However, …