Wednesday, March 25, 2009

some people just can't count

I have a huge sodium hydride reaction going today, almost 100g of 60% NaH, so I've been trapped in front of the hood babysitting all afternoon. It's really boring to stare at that reaction and make sure it doesn't vomit fort it's hateful contents, but is exceedingly preferable to the alternative.

While killing time in between additions I was catching up on some journals and saw this beauty:

I'm impressed by any significant amount of work that can be done in two steps, especially since they seem to add two distinct groups and deprotect in those two short steps. I flipped through the article to find the schemes with the method and its application and came to this:

Scheme 2 shows the appending of the steroid moiety and deprotection in 3 steps. I thought that was odd since they weren't doing as much as they supposedly would in the end, and had already exceeded the alloted steps. I read on and they show the application in scheme 3, and it took 4 steps to get it done. I flipped to the last page only to find out that was it. No more schemes, or discussion. The two step synthesis was completen in a paltry four steps. They were even kind enough to point out in the conclusion that they did indeed perform only two steps (highlighted in yellow), in direct conflict with the scheme. Apparently researchers in California can count vessels as steps. I wonder why they didn't go all the way and call it a domino or multi component reaction?

I also wonder how this made it past review.


sam said...

weird. maybe if you say it enough, it feels like two steps.

Jim said...

Someone just needs to publish guidlines for what you can call a step. I got told the other day that even if you do a filtration its still a one pot reaction. Interesting considering you need two flasks to filter something.

Jim said...

So do you really think that glycosylation or whatever you call goes via an Sn2 mech?

scientist 1 said...

I should have put the whole paper in there, they propose it as a Sn2 mechanism in an earlier scheme. So whether it is or not, I would think of those two things as one step.

I think I'll start referring to purifications as filtrations through a pad of silica with an increasing strength wash. Target compounds in one, incredible, telescope! JACS here I come!

Dr. Miller said...

This reminds me of a paper a student in my group got to review from Baran. He is a habitual exaggerator of how short his syntheses are. Luckily, we required him to revise his step count. One "step" had an aqueous workup and "filtration" through a silica pad. By these standards, all of my total syntheses are one step. Keep you fingers crossed that the editors hold him to our request.

James said...

you could teabag it and call it one pot. I just did a peptide synthesis in "one step" involving lots of washes, reagent changes, etc etc.