Monday, 8 April 2013

#chemclub Roundup: week 6

Double edition! I spent last weekend drinking unhealthy amounts of coffee with old friends, and hence skipped the weekly round-up. On the plus side that means a bumper pack of #chemclub highlights from the last two weeks!

If you've no idea what #chemclub is, read this.

Several people shared what could prove to be a crucial paper from Nature. In brief: X-ray crystallography without the crystals. Derek Lowe has discussed this in more detail; in his words, "Nobel prizes have been given for less".
@clay_owens shares a neat stereoselective synthesis of γ-lactams from readily-available starting materials. The reaction is an auto-tandem reaction, meaning roughly two-step tandem reaction in which both steps - allylic substitution and radical cyclisation - use the same catalyst. The diastereomeric and enantiomeric ratios are consistently above 95%.
Twitter prof @robstockman 's latest paper is out, using the Pd-catalysed cycloaddition of chiral sulfinimines to set stereochemistry in methylenepyrrolidines. The final scheme is a nice touch, demonstrating the synthetic potential of these products.
Longtime fluorine fan @JessTheChemist shares a Science paper presenting experimental evidence for a fluorinium ion. It's an effective approach: make a hideously rigid multiply-bridged molecule, coax a fluorine atom into a likely position for three-membered ring formation, and see where it ends up. Next stop astatinium?
@tonyarash shared several papers recently, but I particularly liked this from JACS. The title sums it up perfectly: meta-selective C-H bond alkylation with secondary alkyl halides. The proposed mechanism involves a Ru catalyst inserting at the ortho position, activating the meta C-H bond to attack. The substrate scope is a bit limited, but otherwise it's a nicely-done piece of work in my opinion.
@Chemistry_Kat, aka the Grumpy Chemist, has a review from Chem. Soc. Rev. on Pd- and Ru-catalysed cross-couplings of sp2 C-H bonds (and related reactions) on (or in) water. Not the first solvent that springs to mind for such reactions, but it turns out that water can enhance catalytic activity under the right conditions.
For those who think eyebrows and, say, limbs are over-rated, @NeilWithers has a #BlogSyn candidate. Specifically, the synthesis of a molecule containing 11 contiguous nitrogen atoms. The first line of the supplementary information reads: "Caution: Proper safety precautions should be taken when handling these compounds. Laboratories and personnel should be properly grounded, and safety equipment such as Kevlar gloves, leather coats, face shields, and ear plugs are recommended.". On the plus side, the 1H spectrum consists of a single peak, making assignment simple even when concussed.
Finally, @nathanbroon dips into some #OldTimeChem. Lurking in the pages of the First Symposium on Chemical-Biological Correlation (1951) is the first ever use of the word "bio-isosteres". Not quite sure why the spine text is written in tipex.
Leave your thoughts in the comments below, and your bedtime reading on Twitter with the hashtag #chemclub.

2 comments:

  1. You can always rely on me for a fluorine fun fact or paper to read!

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    1. True story! Was speaking to the chap selling bench-top NMR machines at #BSM2013 today; apparently they can (or will soon) do fluorine. Could simplify the work-flow for people using 19F-NMR to follow reactions.

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