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Articles Archive for November 2006

Still In The RBF »

[26 Nov 2006 | 8 Comments | 5,168 views]

Paterson and Gardner. Chem. Comm., 2006, Advance Article. DOI: 10.1039/b615122a.
Not strictly a total synthesis, this paper discussed the synthesis of a hybrid of discodermolide and dictyostatin, both previous conquests of the Paterson group. Clearly, from the structures shown below, these molecules are intimately related in construction, and Curran has shown that a constrained macrocycle hybrid may be more potent. This led them to the structure above, containing elements of both molecules, that could be assembled in part from fragments from other work.

I’m not going into a full discussion of the …

Editorial »

[26 Nov 2006 | 22 Comments | 14,595 views]

(Or, Other crap laying around the lab…)

So, poor old Alexander Litvinenko has died in a London hospital; for the truly ill-informed, they guy was an ex-Russian agent, who was poisoned, thought at the time to be thallium.1 His hair fell-out, his white blood cell count plummeted, and two weeks later, he passed-away. Clearly, this incident will have great repercussions in international espionage circles (I’m not stating who I think did it – no ricin-tipped umbrellas for this chemist…), but I’ve been thinking about all that nasty stuff in our …

Still In The RBF »

[26 Nov 2006 | 5 Comments | 8,793 views]

Fecik, Lakshmanan, Salomon and Sherman. JOC, 2006, ASAP. DOI: 10.1021/jo062047u.
An interesting paper, this ‘un. The group are targeting the two macrolides; narbonolide and it’s big brother, pikromycin, using a biotransformation to perform the glycosidation and oxidation. However, they’ve got to make narbonolide first!

As shown in the retro, the linear molecule is constructed through a pair of Evan’s aldols. The synthesis of the constituents was not discussed, primarily because this is a second generation synthesis. These earlier works were generally found wanting in the macrocyclisation, but Fecik and his team excelled, …

Still In The RBF »

[24 Nov 2006 | 17 Comments | 9,232 views]

White, Kuntiyong and Lee. Org. Lett., 2006, ASAP. DOI: 10.1021/ol062530r.
White, Lee and Kuntiyong. Org. Lett., 2006, ASAP. DOI: 10.1021/ol062531j.
I was damn surprised to see a total synthesis of a beast like this ‘un in Org. Lett. today, but I’m afraid that after reading the papers, I’m less so. Obviously, the target has been around for years, and has been pretty popular, with syntheses by Forsyth, Smith, Williams, and Pattenden in the bag. Unsurprising given that tasty-hot cytotoxicity! …

Still In The RBF »

[21 Nov 2006 | 24 Comments | 9,453 views]

Kim, Kim, Lee and Kim. JACS, 2006, ASAP. DOI: 10.1021/ja065782w.
Not one, two, or even three; four total syntheses in this paper, all of medium ring diterpenes, generally with a 9-member ether present in the target. Of course, all originate from a common precursor, and in Kim’s route, from his intramolecular amide enolate alkylation (IAEA) methodology. The original methodology paper was published in 2003 in JACS, followed by an Org. Lett. in 2005 describing their total synthesis of laurencin.

As can be seen with the example above, their methodology is exceptional …

Retrosynthetic »

[19 Nov 2006 | 5 Comments | 5,177 views]

Schetter and Mahrwald. ACIE, 2006, 45(45), 7506-7525; DOI: 10.1002/anie.200602780.
With all this focus on polyketide/macrolide synthesis, I thought I’d highlight an interesting review in this week’s Angewandte; a genuine masterclass in the aldol reaction. They highlight Woodward’s synthesis of erythromycin, an amazing read, just to see how far we’ve come. Also, the figure on page 7507 is incredible; showing the aldol disconnections used in other all of the syntheses of erythromycin so far.

Still In The RBF »

[16 Nov 2006 | 6 Comments | 8,499 views]

Hashimoto, Hirata, Nakamura, Watanabe, Kataoka, Kurosaki, Anada, Kitagaki and Shiro. Chem. Eur. J., 2006, Early View. DOI: 10.1002/chem.200601212.
A second appearance for zaragozic acid on this blog (the first was by Rizzacasa), and a second synthesis by this group (the first). However, there’s been lots of work on this natural product family, most of which construct the ketal using the same approach (Heathcock’s route was an exception). In this synthesis, however, they’ve used a carbonyl ylide cyclisation, an exceptionally elegant route to that complex bridged system.
To make the cyclisation substrate, they …

Still In The RBF »

[15 Nov 2006 | 29 Comments | 10,340 views]

Balwin, Kirkham and Lee. Org. Lett., 2006, ASAP. DOI: 10.1021/ol062361a.
Mehta and Kundu. Org. Lett., 2005, 7, 5569 – 5572. DOI: 10.1021/ol0521329.
Now this is a little scary. Both Sir Jack Baldwin’s group at Oxford and Mehta’s group at the Indian Institute of Science were working on the total synthesis of Spiculoic Acid A. Kundu published the Org. Lett. referenced above, last year, showing their progress towards the target, but it’s taken until now for someone to spot the problems with the paper. Baldwin’s group read the paper …

Still In The RBF »

[14 Nov 2006 | 13 Comments | 6,769 views]

Lee, Kim, An, Shin, Yu, Woo and Jung. ACIEE, 2006, Early View. DOI: 10.1002/anie.200603363.
Another amphidinolide in the bag, this time Amphidinolide E, completed by Eun Lee’s group at Seoul National University. Their approach is very convergent, with an interesting choice of disconnections, some which are obvious, others less so.

So, to the forward synthesis; starting with a known chiral triol, protection with a PMP acetal and reduction of a an ester to the aldehyde gave the starting material for the first interesting transformation, a Roush crotylation. Many of you will have …

Still In The RBF »

[14 Nov 2006 | One Comment | 2,960 views]

And October’s favourite synthesis was Chartelline C. Congrats to the Baran group for this excellent and well appreciated paper.