Won’t you be my neighbor?

Sakthivel, K.; Srinivasan, K. Eur. J. Org. Chem. Early View Apr. 11th 2011

I’m back again, after yet another week of chemistry ownage. Our collaborative projects are fairing well; I can’t wait to tell you more about the details of those projects (all in due course :P). But me and those who must not be named (knock on wood) have been getting along lately. My own research has hit some stumbling blocks, but nothing that can’t be overcome in time. Plus I already have three articles to my name so I’m not that worried. I have to rehash an old issue namely old procedures versus new ones. So I attempted a Tsuji-Trost reaction to access some interesting structures based on an Organic Letters article from 2007. Being the naive chemist that I am, I put my trust in the article completely and attempted to follow their procedure to the letter (which was hard because it was somewhat scarce in detail). Needless to say I was most displeased with the result. Not only did I waste a good amount of time, but I later realized they clearly did not know what they were talking about. Whatever they did, they definitely did not use PdCl2 as their palladium source. I honestly don’t know what they did (or if they did it at all) but I couldn’t replicate their results. But I’m not all that surprised at all. On the flip side, I’ve been doing old procedure that just plain work. No tricks, just followed it (and the thing I liked about this procedure is they even told you what color the solution would turn etc.). There is just something that has been lost in the current literature, probably because chemistry has become too business-like and competitive. But let’s get on with the, at least interesting, chemistry for this week!

Until somewhat recently, I really had not been a fan of EJOC. Most of the stuff coming out really didn’t interest me and none of the names of the authors were all too familar. However, the journal has really grown on me in the past year or so. I don’t know why, but I keep finding interesting articles (like this one) in it on a regular basis. Maybe it is getting a better name for itself or maybe my tastes in reactions have changed, I don’t really know. But regardless, this article really caught my eye. I like simplicity in chemistry. The more complicated it is, the more impractical it becomes. Hence why, while I respect it, I’m not a big fan of most total syntheses. They are great achievements in chemistry, don’t get me wrong, but the majority are of little importance to the greater chemical community. This article, however, is quite practical in its approach.

The article starts out by detailing how important neighboring group participation (NGP), a topic I am quite familiar with :P, is a well-documented phenomenon in organic chemistry. However, it’s less commonly employed as a tool for oxidation. Specifically, oxidation of alkynes using NGP has been quite popular lately. Riding on this trend, Srinivasan’s group has been focusing on the use of the formyl group as a tool for NGP-mediated oxidation. The target was the synthesis of 1,2 diketones, which normal are quite difficult to synthesize and usually require the use of a transition metal. However, this article results more from an accident than from a desire to “go green”. Apparently Srinivasan’s group was trying to replicate some work done by R. C. Larock (see above), but used a “wet” solvent instead of an alcohol as a nucleophile. Their results were in stark contrast to Larock’s as they obtained the tricarbonyl compound instead of the predicted (and probably desired) isochromenol. Fortunately, following their nose ultimately lead them to a new reaction! Not only that but a reaction that is far superior to any other iodine-mediated alkyne oxidation (I know, somewhat specific but still cool!).

Interestingly, their simple reaction conditions did not need to be optimized; they simply just went on to test substrates. And the scope was relatively wide; all sorts of activated and deactivated arenes could be used and even alkyl groups proved amendable to their reaction.They even did a dialkynyl system and formed a hexacarbonyl compound. Moreover, they suggested a pretty legitimate mechanism (which was developed based on deuterium-monitoring studies and investigations with ester and ketone substrates).

They found that an ester was unamendable to formation of the tricarbonyl compounds (they actually formed the isochromenes instead) whereas a ketone also formed tricarbonyl compounds in a similar manner as with the aldehyde substrates. This makes sense since the ester can kick off an alkoxide as a leaving group instead proceeding with the desired mechanism.

Overall, a good read and well presented article by the Srinivasan group. I look forward to seeing more by them and more excellent articles in EJOC. Until next time…Ckellz…Signing off…


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