Friday, July 31, 2015

Friday Fun: Strained Conversation

This graphic was far too funny (to me, anyway) to leave buried in the graphical abstracts...



Courtesy of this Angewandte Chemie paper, in which we learn that "anti-Bredt" olefins - those C=C bonds located at the bridge of a caged bicyclic ring system - don't have to be discarded as possible structures for new natural products. The authors recommend their computational model, which uses modern forcefields to estimate olefin strain (OS) and predict stability of these bridgehead double bonds.

Happy Friday, everyone!
See Arr Oh
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*I know this is a bit belated, but RIP P.v.R. Schleyer. You seemed like a really interesting guy.

Wednesday, July 29, 2015

"But...This Synthesis Goes Up to Eleven!"

Have you had fun reading through all the hilarious send-ups on the Twitter hashtag #HonestChemTitles? This tag tries to dig down to the subtext behind highfalutin words and strange symbols, uncovering the hidden motivations behind scientific papers. And...it's a hoot.

Remember the tweet that kicked off this brouhaha? A harmless convergent synthesis of some Lycopodium alkaloids. Kudos to @AlexFGoldberg for highlighting the authors' rather overblown title:


Classic children's literature;
my first exposure to superlatives
Amazingly, that 10-word title is 30% superlatives and 30% chemistry, with a smattering of conjunctions and articles to connect them. As others pointed out, how do you measure "elegantness," anyway? And when does a total synthesis cross the line from concise to exceedingly so; can anything more than a one-stepper be really succinct?

Sort through the paper with a grammarian's fine-toothed comb; one wonders if it wasn't run through some sort of excitement thesaurus, perhaps to get people really stoked about these routes.

Here's all the intense words and expressions I found:

Diverse
Useful
Unique
Challenging
Efficient
Complete
Direct
Achieved
Accomplished
Value
Exceedingly concise and convergent
Attractive

...and that's just in the first paragraph, folks.

Nigel Tufnel (Christopher Guest), ca. 1984
Honest opinion? Aside from the goofy title and superlatives liberally sprinkled into the text, the chemistry seems solid. Nothing's breathtaking - setting an early quaternary center through steric control is nice, and telescoping the three steps before the desired tetracyclic dione works well - but there's no "killer reaction" for me in this paper. The NMRs are clean, and the synthesis represents a decent improvement over existing methods.


Thus, I'd like to accept this publication into the "Spinal Tap Synthesis" category, so-named for the hard rock auteurs profiled in 1984's This is Spinal Tap, the tongue-in-cheek rock mockumentary. If you've never watched the movie, I won't spoil it, but I highly recommend the sequence in the middle where Nigel Tufnel, the vapid, misunderstood lead guitarist, obsesses over a "special" amp he designed that "goes to 11."

Fits this paper to a T.

Friday, July 17, 2015

Friday Potpourri: MegaMan, Lab Coats, More Worms

Please excuse my general lack of posting. When "Big Work Project" finally wraps, I'll have a bit more time for chemistry frivolity. In the meantime, how about a little collection of  almost-posts to help you into your weekend?

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Faculty Fun: Maintaining a list of faculty moves can be tedious, but sometimes you find little gems on group pages. For example, Jeff Rinehart's group at UCSD will study magnetic materials. The logical mascot? A MegaMan master robot! (Vittorio would be so pleased...)

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Last month, thought-provoking Chemistry World columnist Philip Ball wrote about white lab coats as badges of professional scientific stature. You may recall that one of my first posts here at JLC referred to the many ways in which such a white coat could be spoiled. I'm not exactly certain why - supplier availability, fire resistance, styling, cheaper? - but chemists in some younger synthetic organic chemistry groups seem to prefer blue lab coats.
Need evidence? Click below:

Phil Baran group
Stephenson group
Meek group
Shenvi group

(Readers: Know of more indigo-hued groups? Please mention in the comments)
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Finally, for fans of vermisynthesis (who isn't?), you may notice that the chemblogosphere is giggling about this recent Tetrahedron paper on catalytic earthworms. Quintus points back to a 2014 PLoS One, but how far back have chemists truly considered the lowly earthworm as synthetic feedstock? Professor Leonardo Santos of the University of Talca, Chile, has investigated bioreduction of beta-carbolines since at least 2013. Perhaps he was inspired by the work of Kohji Ishihara, who published similar reductive behavior in cell-free worm extracts back in 2006. And both should potentially thank D.Q. Keiline, a reference in Ishihara's manuscript, who back in 1920 published "On the pharyngeal or salivary gland of the earthworm," which portended some of the proteolytic enzymes found therein.

Worm salivary glands (s.gl. in picture). You're welcome.
Source: Keiline, 1920

Tangentially, it's worth noting that an engineer in Colombia recently commercialized "biofilters" made of (living) earthworms, which clean organic solids from waste water. Seems someone should take a harder look at the potential catalytic goldmines wriggling underfoot.

Happy, squirmy Friday, everyone!
See Arr Oh

Thursday, July 9, 2015

What Happened to EJCorey.com?

A few years ago, folks on Twitter were helping me to collect a list of superlative chemistry authors - those in the rarefied air of hundreds to thousands of published scientific articles. At the time, I had counted Nobelist E.J. Corey's papers by visiting his personal website, linked from his Harvard emeritus faculty page

Curious, I returned there this week to view some of his recent research, and found this splash page:


1. Does this mean that the domain name is available?
(Checks - nope, someone has it, but GoDaddy will gladly sell you ejcorey.guru or ejcorey.expert!)

2. If you were the Harvard chemistry department, wouldn't you take steps to ensure that your emeriti had a guaranteed web presence? Prof. Dave Evans' fantastic site comes to mind.

Anyone have more information on when we can expect Prof. Corey's site to come back?

Tuesday, June 30, 2015

Smells Like Chemistry Prose

From the April 2015 issue of Wired magazine, two wonderfully redolent paragraphs regarding the flavor chemistry of yeast metabolites, courtesy of writer William Bostwick:
"The best sourdoughs command the same sort of cultish reverence as the best sour beers and for years were thought to come only from a few places. San Francisco's loaves are so famous, a Lactobacillus species is named after the city: L. sanfranciscensis, known for molecules like fruity isobutanol, butter-sweet acetoin, and grassy 1-hexanol."
If you're more a fan of lambics, perhaps this flavor profile better suits you:
"Pediococcus produces lactic acid, lambic's dominant flavor note, but can also emit funkier flavors such as buttery diacetyl. . . Brettanomyces also makes stuff like caprylic acid (goat smell) and ethyl lactate (horse-blanket smell). They're what make a farmhouse beer taste like a farm."
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*(Title: Apologies to Nirvana).

Monday, June 29, 2015

(Please) Make More Molecules using Light!

Update (6/29) - Commenters chime in with some notables I'd mistakenly left off the list. I'll append their molecules to the end of this post (vide infra)...

I'm officially calling it: Photoredox catalysis = the new "it reaction" for organic chemistry.

Like many before it - iron catalysis, the gold rush, anything palladium, organocatalysis - photoredox catalysis is now appearing in my RSS feed on a near-hourly basis. We're in the early days of an exciting field; I've noticed more methodology papers and mechanistic studies lately. Assuming you start with a suitable aryl halide, diazonium, or carboxylic acid, the synthetic toolkit of single-electron catalysis seems virtually limitless.

Which begs the question . . .where are all the photoredox total syntheses?

Three examples of recent total syntheses that capitalize
on photoredox catalysis (bonds in red)
SciFinder: "photoredox total synthesis?"
7 hits.

How about "light-mediated total synthesis?"
7 more.

One more try: "photoredox natural products?"
7 hits.

Most of these hits actually lead to conference abstracts, not individual manuscripts. Props to the Stephenson group (Michigan), who leads the charge with syntheses of aspidosperma alkaloids and gliocladin C. Based on SciFinder results, I'd include the MacMillan synthesis of Lyrica, and Lei's isoquinoline syntheses from JOC.

Readers, what am I missing? A pivotal review or book? A group whose research is at the forefront of solar-powered natural product production? Perhaps a major non-English journal article? Any examples where a venerable old lion of total synthesis utilized a photoredox reaction alongside their Diels-Alders and aldol reactions?

For such a large-upside field, it sure seems quiet out there.
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Update: Molecules made with photoredox catalysis, as suggested by my beloved commenters:

Overman, (-)-aplyviolene, Ru(bpy)3
MacMillan, fenofibrate (OK, not a np), Ni(II), Ir(III)
MacMillan, (-)-burshernin, Ru(bpy)3
Nicewicz, methylenolactocin and Protolichesterinic Acid, acridinium
Nicewicz, magnosalin + pellucidin A
Yoon, heitziamide A, Ru(bpz)3
Yoon, epiraikovenal, Ir(III)
Chen + Baran, sceptrin, Ir(ppz)3
Chen, nakamuric acid, Ir(ppy)3
Lawrence / Sherburn, endiandric acid A, kingianins A,D,F, kingianic acid E, Ru(bpy)3
Carreira, (+)-Daphmanidin E, Co-diimine (method here)

More?

Friday, June 26, 2015

Friday Fun: Google Scholar Surprises

From Google, a.k.a. the guys with all the data, comes the most recent Google Scholar metrics.

I'm starting to really enjoy the level of specificity Google's learned around academic sub-fields. For instance, in my own sub-field of organic chemistry, who knew that Green Chemistry and Molecules were rising so quickly through the ranks of top-cited publications?

The h5-index Google's using seems like a shot across the bow of the venerable Thomson Reuters Impact Factor. A glance through the top-cited papers across all of chemistry, couched in this 5-year zetigeist, shows some surprising trends in the field: tunable materials, solar conversion, nanoparticles, and genomic medicine win the day - nary a major total synthesis among the top-cited 'scripts of any journal I could find.

If you have a minute, play around - the Google site is clean, easy to navigate, and provides direct links to publications of interest. If you stumble across anything surprising, let me know in the comments!

Happy searching, Happy Friday!
See Arr Oh