clearly_not_atara
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A nearly-OTC enantioselective homogenous ruthenum reduction catalyst
The price of ruthenium is about one-fifth of the price of palladium. It's not cheap, but an 80% discount is nothing to sneeze at, right? The
catalyst is active at 0.5 mol% loading with formates as reductant.
https://onlinelibrary.wiley.com/doi/full/10.1002/tcr.2016000...
Compound 7 is a complex formed between RuCl2 and N-phenethylsulfonyl-1,2-diphenylethylenediamine. The requisite sulfonyl chloride can most likely be
prepared by using Ullmann's method starting from phenethyl bromide as described here:
https://www.sciencemadness.org/talk/viewthread.php?tid=9921&...
The compound 1,2-diphenylethylenediamine can be prepared as described on Orgsyn:
http://www.orgsyn.org/demo.aspx?prep=CV9P0387
The great thing about Orgsyn is the procedures work. In this case benzil is the starting material, which can be prepared from benzoin, by:
1. benzaldehyde + catalytic thiamin
2. Cu(OAc)2
The resulting complex (assuming you resolved the DPEDA) reduces ketones and imines enantioselectively, which is kind of interesting. Compound 7 was
reported to be effective but not especially great; we'll take what we can get (usually).
Notably, while some older references, such as this one:
https://pubs.acs.org/doi/abs/10.1021/jo01068a043?journalCode...
mention Ru-catalyzed debenzylations, I don't find any examples in the recent literature.
[Edited on 04-20-1969 by clearly_not_atara]
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Tsjerk
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Very cool, I like the fact you only have to do the tartaric acid precipitation resolution once and you are set with catalyst for life (opposed to
tartaric acid resolution of an given compound after reduction to the amine or alcohol).
[Edited on 27-11-2018 by Tsjerk]
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zed
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Yup! Ruthenium isn't cheap right now. A year or two ago, it was around 60 bucks an ounce.
Still the same old Ruthenium, no earth shaking discoveries have occurred.
So, probably at a speculative price peak, right now.
Might be back at 60 bucks an ounce, by this time next year.
http://www.infomine.com/investment/metal-prices/ruthenium/al...
[Edited on 28-11-2018 by zed]
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