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Articles Archive for August 2009

Still In The RBF »

[30 Aug 2009 | 42 Comments | 16,159 views]
6-deoxyerythronolide B

White, Stang. Nature Chem., 2009, AOP. DOI: 10.1038/nchem.351.
Nice to see a bit of total synthesis in Nature Chemistry this month – but to be fair, this is more about the organometallics than the macrolide.  But if you’re going to prove some methodology – especially, as in this case, macrolactonisation, this is a good target to work on.  6-deoxyerythronolide B (6-dEB) is a typical polyketide macrolide, and I mean that chemically, as the configuration of the stereocenters is very much the norm.  This meant two things – …

Still In The RBF »

[25 Aug 2009 | 8 Comments | 12,125 views]
Sorangicin A – pt. 2

Smith, Dong, Brenneman, Fox. JACS, 2009, ASAP. DOI: 10.1021/ja9052366.
Read the first post?  Good.  Let’s get on with the one remaining fragment, a further DHP.  Work on this fragment was conducted via a coupling of an enone with the ready-elaborated sidechain – reaction that might be a little sluggish, as the enol functionality is again working against the group.  However, forming a cuperate of the vinyl bromide solved this, allowing a highly selective and reasonably high yielding reaction (60%, 20:1 d.r.).  BTW, the two fragments weren’t particularly …

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[23 Aug 2009 | 5 Comments | 10,270 views]
Sorangicin A – pt. 1

Smith, Dong, Brenneman, Fox. JACS, 2009, ASAP. DOI: 10.1021/ja9052366.
I thought I’d re-start after holiday with a tasty target, and sorangicin A certainly fits the bill.  It’s not often that I have to draw such an exotic structural motif into a target (though in reality it’s not far removed from a DHP); always a welcome feature in a synthesis.  But sorangicin A is more than just a structural challenge – it’s quite an antibiotic, with broad-spectrum activity against both Gram-positive and Gram-negative strains.  With the funding proposal …

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[15 Aug 2009 | 18 Comments | 13,331 views]
Holiday time!

I’m off to Holland for a week; being given the grand-tour by my girlfriend.  More total synthesis action on my return – starting with Amos Smith’s synthesis of Sorangicin A.  Neat stuff.  However, that post ish not yet rready…

Still In The RBF »

[10 Aug 2009 | 36 Comments | 13,923 views]
Dioxepandehydrothyrsiferol

Jamison, Tanuwidjaja, Ng. JACS, 2009, ASAP. DOI: 10.1021/ja9052366.
Capitalising upon his pontifications analyses in Science (2007), Tim Jamison has come-up with the goods; a poly-epoxide cascade to build a poly-ether.  He’s not the only one – Frank McDonald crafted a nice synthesis last year using the same principles.  However, Jamison has upped the epoxide count, controlling formation of three ether rings in one go.
As ever, the initial trial is construction of the linear, poly-epoxy precursor – with few surprises in Jamison’s route.  The starting material is farnesol, …

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[3 Aug 2009 | 11 Comments | 11,294 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 …