Chemistry World: Platencin
5 September 2008
8,072 views
22 Comments
Latest piece for the RSC in the September issue of Chemistry World
(No Ratings Yet)
Loading ...Chemistry World: Platencin
(No Ratings Yet) Loading ...
Another nice piece..
Good write-up on MacMillan’s latest Science paper too in this issue..
Just out of curiosity: why wasn’t Mulzer’s synthesis of platencin discussed? His synthesis — which was published before Rutjes’ — also conveniently utilizes perillaldehyde. Moreover, his “endgame” after the Diels-Alder was much more concise.
totally agree with DK. Not mentioning Mulzers synthesis when speaking about Rutjes approach is strange.
ets look at the facts:
starting material: perillaldehyde in both cases
Mulzer: Received: 26 March Rutjes:Received: 18 June
Mulzer: 5 steps Rutjes: 9 steps
Mulzer: no PG Rutjes: 1 or 2 PGs depending on if the . acetate is fully counted
How in the world does that selective oxidation in Nicolaou’s approach work? Seems like they got lucky there…either that or a grad student suffered, heh.
nice piece of work…
i liked the final oxidation..
the allylic oxidation was from a Org lett reference…
what is the bp of the right hand fragment??? How easy is it to lose it in high vac?
simple unsubst decalin has bp over 185C so I would not worry too much
Also, the W-M ketone analogue derived from ethyl vinyl ketone is a crystaline solid, so once again, probably not much to worry about there.
Is that a paper from K.C. as shown in DOI: 10.1002/anie.200800066 was the fist one instead of
Rutjes or Mulzer? Paper was received in Jan 7, 2008 and published in angew.Che. Int. Ed. 2008, 47, 1780.
Please clarify if I am wrong.
Thank you,
AJ. yes. the first synthesis is by nicolaou which is also not mentioned in the article. but what DK and I meant is that the Mulzer synthesis is based on the same approach as Rutjes but with a more concise “endgame” and was published much earlier than Rutjes paper. Since it utilizes the same starting material and related first steps it should be mentioned when talking about “Rutjes approach”.
Sorry for the off-topic but do you, guys, manage to store triflic acid? If yes, then how?
,,,
You can always just open the ampule in a glove bag and transfer it to a schlenk that’s already been put under argon.
Yeah, tried that… Not more than a week and then it darkens… Thanks anyway. Maybe just prepare fresh schlenk every week…
we had a bottle from the supplier (some flouride company I believe) that never darkened. don’t even think we took especially great care of it. had it for well over a year and a half. sure you’re not referring to triflic anhydride? that’s an entirely different story.
I have found that if you store TfOH in a pear shaped flask capped with a teflon cap on a bed of drietrite (blue dehydrating agent) with the bottle capped in the fridge, it does not usually go that bad.
Indeed, I kept it in a schlenk with teflon valve. Maybe putting some indicating drying silica is not a bad idea…
I just transferred the Aldrich ampoule content into a normal, clean 100mL brown bottle a with teflon-lined cap, bought from Fisher,.and it stored quite nicely at RT in dark under hood for about a year and was still colorless. The main thing is to avoid impurities from the cap liner, TfOH dissolves lots of things and then goes brown… far worse in this respect than sulfuric acid or TFA
Hey guys, do you have an idea of the mechanism reduction of azides by a thiol as the 1,3-propanethiol in the presence of a base ?
I think the mechanism should be similar to reduction with phosphines. But I dont know for sure.
The R-N(-)-N=N-PR3+ adduct is isolable, and it colapses through 4-membered ring transition state to .R-N=PR3 and N2.
I suppose RNHSR species promptly reacts with another molecule of thiol to produce disulphide and free amine.
Disulfur specie is isolated a the end of the reaction. After reflexion, I propose this mechanism :
http://img521.imageshack.us/img521/5500/redazoturethiolwl0.gif
Are you agree with this ?
I dont know if this sheme you drew is correct. I would expect that – after the thiol addition – the second nucleophilic attack should happen on the first nitrogen so that you get R’NHSR (and N2 as a leaving group). Another molecule of thiol then gives you RSSR and R’NH2