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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: AlphaScent on April 03, 2019, 10:55:44 AM

Title: Sharpless AD without ligand (DHQ)2PHAL (AD-mix alpha)
Post by: AlphaScent on April 03, 2019, 10:55:44 AM

Hey all,

Can you do Sharpless conditions without the chiral ligand (DHQ)2PHAL.  Is K3Fe(CN)6 viable as a stoichiometric oxidant for the dihydroxylation without the presence of the ligand.  My quick search makes me think it should be fine.  I do not mind if I get racemic.  The mechanism based on the first page to Meyers' lecture seems to be that it should be fine.

http://hwpi.harvard.edu/files/myers/files/23-sharpless_asymmetric_dihydroxylation_reaction.pdf

Any thoughts are much appreciated!

Cheers!

Title: Re: Sharpless AD without ligand (DHQ)2PHAL (AD-mix alpha)
Post by: AlphaScent on April 03, 2019, 10:57:31 AM

Sorry I am just wondering about this.  My plan is to use Upjohn's conditions most likely.  Wanted to clarify my thinking.

Cheers!

Title: Re: Sharpless AD without ligand (DHQ)2PHAL (AD-mix alpha)
Post by: rolnor on April 03, 2019, 11:05:11 AM

It should be fine without the ligand. I have used OsO4 with periodate but then you get the aldehyde.

Title: Re: Sharpless AD without ligand (DHQ)2PHAL (AD-mix alpha)
Post by: AlphaScent on April 03, 2019, 12:23:51 PM

Good to know rolnor.  Appreciate it.

I think I am just going to try it and see.  To be honest I was lazy today and haven't dove into the literature.  I will read the paper on the potassium ferriccyanide reaction on that Meyers' page.

Thanks again! 

Title: Re: Sharpless AD without ligand (DHQ)2PHAL (AD-mix alpha)
Post by: AlphaScent on April 03, 2019, 01:14:42 PM

I shouldn't have been lazy.

Osmium tetraoxide catalyzed vicinal hydroxylation of higher olefins by using hexacyanoferrate(III) ion as a cooxidant (https://pubs.acs.org/doi/abs/10.1021/jo00289a066)
J. Org. Chem., 1990, 55 (2), pp 766–768
DOI: 10.1021/jo00289a066 (http://dx.doi.org/10.1021/jo00289a066)