Wednesday, 27 March 2013

#chemclub Roundup: week 5

Here are a few highlights posted to #chemclub this week. (What's #chemclub, I hear you cry? Answers lie within.)

First up: Nessa shared an impressive 20-step (total) convergent synthesis of 6-deoxyerythronolide B, a precursor to erythromycin and classic target of synthesis. The synthesis is by Krische in JACS I won't say anything more on it: the article she linked to is a great discussion!

As usual, @Total_Synthesis has a good paper for us. In Nat. Chem., Xiao et al. report the synthesis of a family of natural products by two different and concise routes based on multiple [3,3]-sigmatropic rearrangements. This approach allows the stereochemistry of tatanan A to be set by asymmetric CBS reduction and then transferred to other atoms, where stereochemistry might otherwise be tricky to install. The route to tatanans B and C is rather different, although the authors originally attempted to synthesise them from tatanan A biomimetically.

@V_Saggiomo shares a Diels-Alder based synthesis of enormous dendrimers. The molecules are seriously huge: the biggest is a 33 nm particle with a mass of 1.88 mD, containing 18,402 phenyl rings and 2,048 chain ends. The structures are well-defined, with a polydispersity index of at most 1.005 (by MALDI). Somehow these beasts are soluble in most solvents, and were characterised as fully as any small molecule is ordinarily. I don't even know what to say about this.

My own contribution: a room-temperature catalytic Wittig reaction, improving on previous reports that went at 100 °C. It's early days yet, and there are still a few issues to work out, but the E/Z selectivity gets as high as 90/10 and yield up to 75%.

And finally, a question from @clay_owens:

Which journals do you read regularly? Which do you like the most? I really enjoy Org. Lett. and Chem. Eur. J.: often find great papers in both, and I find the format very easy to read quickly.

1 comment:

  1. I'm trying to get into Adv Synth Catal a bit more.

    Organometallics is up there amongst my favourite journals to browse through when I'm not looking for anything in particular.