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Articles tagged with: metathesis

Guest Post, Still In The RBF »

[6 Aug 2011 | 17 Comments | 15,856 views]
Omphadiol

Romo, Liu. ACIEE, 2011, 50, 7537-7540. DOI: 10.1002/anie.201102289
Guest Blogger: SPF
What if I’d ask you to synthesize this little molecule with six neighbouring stereocenters from biologically available material? Oh, by the way you can’t use any protecting groups and keep it short! Sounds impossible? Not according to Romo et al.. They’ve achieved the synthesis of this stereo-dense molecule in 10 steps from (R)-carvone (Mmmhhh spearmint). (+)-Omphadiol belongs to the africanane (guess where they grow) family of sesquiterpenes. Its brothers and sisters show some significant bioactivity, but due to insufficient …

Still In The RBF »

[24 Oct 2010 | 116 Comments | 61,754 views]
Lycoflexine

Ramharter, Mulzer, Weinstabl. JACS, 2010, 132, 14338-14339. DOI: 10.1021/ja107533m
I love the fact that one can just look at a molecule and then guess the author of the synthesis.  And when I first glanced at Lycoflexine, the name Johann Mulzer was at the top of my mind.  (However, on closer inspection, the starred author is one Juergen Ramharter, even though Mulzer is also named…)  This makes me smile for two reasons – firstly, Mulzer always works on small, yet interesting targets.  Secondly, I routinely learn something new in his work.
To say …

Still In The RBF »

[18 Jan 2010 | 16 Comments | 16,407 views]
Hyperforin

Shibasaki, Kanai, Shimizu, Shi, Usuda. ACIEE, 2010, EarlyView. DOI: 10.1002/anie.200906678. ; Shibasaki, Kanai, Kuramochi, Usuda. Org. Lett., 2004, 6, 4387. DOI: 10.1021/ol048018s. 
Three amazingly tough targets completed in (almost) as many months – you can’t tell me that total synthesis is stifled.  Hyperforin has been staining the white-boards of many a lab for decades – the isolation (reported in Antibiotik…) was way back in ’71, and has resisted synthesis until now.  Shibasaki himself has been working on it for quite a while, as you’ll have seen in the header – a key …

Still In The RBF »

[17 Nov 2009 | 32 Comments | 15,404 views]
Fostriecin

McDonald, Robles. Org. Lett., 2009, ASAP. DOI: 10.1021/ol902365n.
It’s been a little while, but there’s been nothing too exciting (total synthesis-wise) in JACS or ACIEE.  However, a quick glance in Org. Lett. produced a veritable cornucopia of syntheses, with this lesson in catalysis nudging to the fore.
The target is a newbie to this website and to me too – but not to the chemical community at large.  Indeed, the list of prior syntheses is quite unnerving for the prospective student-synthesizer, including Kobayashi, Boger, Cossy, Shibasaki, Reddy…  This brings a certain amount of knowledge, …

Still In The RBF »

[11 Oct 2009 | 36 Comments | 15,930 views]
Aigialomycin D

Barrett, Calo, Richardson. Org. Lett., 2009, ASAP. DOI: 10.1021/ol901979x.
Macrolactones?  From Barrett?  It’s not his usual fayre, but as is more normal, there is a twist in the synthesis.  I think most chemists (or at least me…), when presented with a target like aigialomycin, would think about buying-in the aromatic portion, and then trying to bolt on the styrene-type olefin and building around.  However, with his interests in reactive intermediates, Tony Barrett (of IC, London… just down the road), it comes of no real surprise to me that he …

Still In The RBF »

[3 Aug 2009 | 11 Comments | 11,461 views]
Hygromycin A

Donohoe, Flores, Bataille, Churruca. ACIEE, 2009, ASAP. DOI: 10.1002/anie.200902840.
Sugar bashing time!  It’s been ages since I glanced at sugar synthesis, probably because I developed an irrational phobia whilst at Oxford.  Not because of the intricate syntheses, the illogical reactivity patterns, or the ridiculous names (psychose psicose, anyone??) – but for the shear quantities of potassium cyanide used by the Fleet group in their Kiliani Ascension chemistry.  Probably time I got over that, so we’re staying with the folks at the old place, and a bit of …

Still In The RBF »

[14 Jul 2009 | 20 Comments | 11,738 views]
Polyanthellin A

Johnson, Campbell, Qi. JACS, 2009, ASAP. DOI: 10.1021/ja904136q.
Sorry for the lack of blogging, folks – I’ve been feeling a bit under the weather, but I assure you, it’s not H1N1…  However, it seems like the res of the world is getting on with it, with several nice syntheses in JACS just now.  Lyconadin A is headed for Chemistry World, later this month, whilst plicatic acid is line behind polyanthellin A. Hopefully, sticking the latter into the Tot. Syn. search box (operated by trained hamsters) will …

Still In The RBF »

[2 Jun 2009 | 24 Comments | 11,233 views]
Ricciocarpin A

List, Michrowska. Nature Chem., 2009, AOP. DOI: 10.1038/nchem.215.
Another rather short blog post, but why wax-lyrical when the synthesis is short and sweet?  Ben List is still hammering-away at his niche in organocatalysis, this time reporting a rather nice domino reaction.  The target of the synthesis is a isolate of a liverwort, and possesses “potent molluscicidal activity” – not a biological effect I’d come across before.  It turns out that this natural product spells doom for Biomphalaria glabrata water snails…  and we’re still at a loss.  Water …

Still In The RBF »

[10 May 2009 | 31 Comments | 12,610 views]
Amphidinolide X

Lee, Jung. ACIEE, 2009, EarlyView. DOI: 10.1002/anie.200900865.
Another month, another amphidinolide – but we’re getting pretty close to the end of the alphabet now.  Actually, I’m (as ever) being rather over-the-top – we’ve not actually covered that many, but X & Y (as well as being an affront to my ears) were blogged in 2006, where the focus was on the THF synthesis.  This is the case again with Eun Lee’s synthesis, which almost disregards the polyketide-style sections.
The key to his synthesis of the THF is a …

Still In The RBF »

[16 Feb 2009 | 17 Comments | 12,520 views]
Norhalichondrin B Pt. I

Phillips, Jackson, Henderson, Motoyoshi. ACIEE, 2009, EarlyView. DOI: 10.1002/anie.200806111. Article PDF Supporting Information Group Website

As I said in the last post, it was a rather quiet fortnight for total synthesis, at least as the big journals go. However, I think Andy Phillips can feel justified in his absence when he’s been cooking molecules like this ‘un up. Norhalichondrin B is part of the halichondrin family, isolated about twenty years ago – plenty of time for a bit of synthetic action, kicked off by Kishi back in ’92. Impressively, the synthesis hasn’t been entirely academic, with the peeps at Eisai Pharma also working on analogues. So how to start (lots of grant-application forms…)?