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Articles Archive for June 2006

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[29 Jun 2006 | 4 Comments | 10,242 views]

Sorry folks, but there’ll be no new posts for the next week or so, as I arrange internet access at my new address. Y’see, I’m on a placement in industry now, so no dossing about on the internet at work time to work in the evenings. Normal service will return ASAP, but for now, do check out:
Two new syntheses of Clavosolide A: DOI: 10.1021/ol0611705, DOI: 10.1021/ol0611752.
And as mentioned by our dedicated team of commentators, Gin’s synthesis of Nominine: DOI: 10.1021/ja062543.

Still In The RBF »

[24 Jun 2006 | 5 Comments | 7,221 views]

Fürstner, Kattnig, and Lepage. JACS, 2006, ASAP. DOI: 10.1021/ja061918e.
Another pair of amphidinolides in the bag, Furstner et al. have completed the synthesis of X (the only member of the series with an even-numbered macrocycle) and Y using a powerful iron catalysed process. Both products (as with most of the family) are cytotoxic, and contain the heavily functionalised THF moiety. This allowed the group to create an intermediate common to both campaigns, starting from a simple epoxide produced from an SAE.

Treatment of this with n-propyl grignard and catalytic quantities of the …

Still In The RBF »

[21 Jun 2006 | 8 Comments | 5,354 views]

Sasaki, Shoji, Akiyama, Tsubone, Lash, Sanders, Swanson, Sakai, Shimamoto and Oikawa. JOC, 2006, ASAP. DOI: 10.1021/jo0605593.
This target came up in our group problems a few weeks back (thanks Steve), and Sasaki et al. have provided a very neat solution to this small yet complex molecule. Isolated from the sponge Dysidea herbacea, it is a excitatory amino acid, containing a glutamic acid unit attached to a cis-fused 5,6-pyran ring system. I’m not going to discuss it here, but it shows an interesting and potent biological …

Retrosynthetic »

[16 Jun 2006 | 6 Comments | 6,240 views]

Farina, Reeves, Senanayake, and Song. Chem. Rev., 2006, ASAP. DOI: 10.1021/cr040700c.
Interesting review of all-manner of asymmetric synthesis of drug targets, using chemistry that presumably “works”!!

Still In The RBF »

[15 Jun 2006 | 13 Comments | 12,588 views]

Baran, Hafensteiner, Ambhaikar, Guerrero, and Gallagher. JACS, 2006, ASAP. DOI: 10.1021/ja061660s.
Detailing their syntheses of three related natural products in this article, Phil Baran’s group have been working rather hard on this funky dimeric natural product. Created via the spontaneous dimerisation of avrainvillamide, their synthesis of this series is incredibly compact. To the business end:

Thus, the synthesis plan now requires a construction of the monomeric unit, which begins with an impressive piece of new technology. Using palladium catalysis, they have developed a route to substituted tryptophans from simple precursors, inspired by …

Still In The RBF »

[14 Jun 2006 | 5 Comments | 5,637 views]

Baldwin, Kirkham and Lee. Chem. Comm., 2006, Advance Article. DOI: 10.1039/b607035c5
Not just the total synthesis here, but also the assignment of the absolute configuration, Jack Baldwin et al. have used a really nice DA to assemble the 6,5 system. Starting back at the aldehyde, a Wittig olefination completed the tethered acyclic substrate for the DA, which spontaneously cyclised at 100 ºC. Nice way to construct two …

Still In The RBF »

[14 Jun 2006 | 5 Comments | 6,771 views]

Movassaghi, Hunt and Tjandra. JACS, 2006, ASAP. DOI: 10.1021/ja0626180
Movassaghi et al. at MIT have completed a nice synthesis of Galbulimima alkaloid 13, using some smart cyclisations. Related structures have shown potential as Alzheimer’s disease treatment”s, so this class of structure could be very useful.

A simple DA [4+2] installs the A and B rings with excellent endo : exo selectivity, and leads to the next cyclisation substrate after a few steps.

Radical abstraction of the vinyl bromide led to cyclisation onto the alpha,beta-unsaturated imine, …

Still In The RBF »

[11 Jun 2006 | 6 Comments | 6,785 views]

Stoltz and Tani. Nature, 2006,441 (7094) pp 731 DOI: 10.1038/nature04842
Just a quick postlett (I might trade-mark that…) to point out Stoltz’s total synthesis in Nature, as mentioned by “ddd” in the previous post’s comments. This little beasty has been the burden of much discussion and controversy in the community, and the accompanying X-ray is very interesting. Y’see, it’s an anti-Bredt amide, where the nitrogen LP has been forced out of conjugation from the carbonyl, resulting in a radically different amide chemistry (the N behaves much more like an amine).

After a …

Still In The RBF »

[7 Jun 2006 | 12 Comments | 5,743 views]

Crimmins and Vanier. JACS, 2006, Org. Lett. DOI: 10.1021/ol061073b
A dimeric beasty, Crimmins and Vanier have completed the synthesis of the snappily named SCH 351448 with a demonstration of some of the most powerful and useful synthetic methods in organic synthesis. A popular target (with three previous syntheses), their work was completed in 30 steps (LLS), generating the only known selective activator of LDL-R (low-density lipoprotein receptor). All but two of the stereocenters were established through chiral enolate reactions, demonstrating deft usage of a variety of chiral auxiluaries and aldol chemistry. …

Still In The RBF »

[4 Jun 2006 | 13 Comments | 14,348 views]

Total Synthesis: La Clair. ACIE, 2006, 45, 2769. DOI: 10.1002/anie.200504033

Stuctural Reassignment: Rychnovsky. Org. Lett., 2006, ASAP. DOI: 10.1021/ol0611346

After reading some very interesting discussion at Dylan’s Tenderblog, and receiving this request, I’ve decided to post on this intriguing issue. Some months back, La Clair at the Xenobe Research Institute (San Diego) published the first total synthesis of hexacyclinol. This synthesis was an impressive piece of work, including an interesting [2+2+2] step to put in the peroxide.

Based on the isolation by Gräfe, using structure 1 as the target, this work now seems …