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Author: Subject: Synthesis help
Tankcsapka
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[*] posted on 3-9-2019 at 09:07
Synthesis help


Hello everyone!

I need some help with some of the steps in the following synthesis:

KingDraw190903165221(1).PNG - 45kB

The first two steps are pretty straightforward, mild oxidation of the alcohol to an aldehyde followed by conversion to an amino acid.

I am unsure about the viability of the HI reduction method. The Practical Methods Of Organic Chemistry states that HI can be used to convert carboxylic acids to the corresponding alkane, but it does not say in which solvent. Would an organic solvent work instead of water? I fear the acidic HI would deprotect the amide, then reduce it to an amine. Should one use a catalyst to absorb the HI or a polar aprotic solvent in which the HI is soluble?

Thanks for your insights!
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chemistry007
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[*] posted on 3-9-2019 at 11:27


It looks that the solvent is writen in the reaction: PhCH3...it's toluene...no?
Change it to alcool and then probably it can be easier to reduce the alcool with HI
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Mush
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[*] posted on 3-9-2019 at 11:31


Reduction of benzylic alcohols and α-hydroxycarbonyl compounds by hydriodic acid in a biphasic reaction medium

"Toluene and aqueous hydriodic acid are a suitable biphasic reaction mixture for the reduction of a range of benzylic alcohols."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3302097/

IMO HI will cleavage of ethylene dioxy group in this case.

[Edited on 3-9-2019 by Mush]
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CuReUS
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[*] posted on 4-9-2019 at 06:47


Firstly,ketones and amides don't behave the same way.Glycol doesn't react with amides to form ketals.
Quote: Originally posted by Tankcsapka  
I fear the acidic HI would deprotect the amide, then reduce it to an amine.
That' the least of your worries.HI can destroy the complete lactam ring as well as take out the F atoms

What is your target compound and your starting materials ? Perhaps a better route could be suggested.
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