December 22, 2024, 01:06:33 AM
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Topic: Interesting part of Ivanov Reaction  (Read 1893 times)

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Offline zsinger

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Interesting part of Ivanov Reaction
« on: April 27, 2014, 01:28:50 PM »
All,
After the 2 Grignard equivalents have been added to the reaction, why does one get a "pseudo-enol" (Maybe call it a di-enol?)?  I ask because I am curious why said Grignard initially coordinates to BOTH the alcohol and the ketone, whereas, normal conditions dictate the ketone itself being attacked, as the alcohol is not nearly electrophilic enough to accept the hot Grignard nucleophile (nearly ionic in strength and negative charge density!)
                -Zack
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Offline Archer

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Re: Interesting part of Ivanov Reaction
« Reply #1 on: April 28, 2014, 04:00:07 AM »
I am not sure I follow what you are asking but if I have understood, you don't get an enol or dienol you get an geminal dienolate becuase the grignard has acted as a base and not a nucleophile in this first step owing to the relatively low pKa of the carboxylic acidic proton and the protons alpha to the carboxylic acid.
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Offline zsinger

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Re: Interesting part of Ivanov Reaction
« Reply #2 on: April 28, 2014, 01:48:12 PM »
Archer,
Thanks…..I got it now.  I also asked my graduate advisor, and he gave me nearly a carbon copy explanation of yours!
             -Zack
"The answer is of zero significance if one cannot distinctly arrive at said place with an explanation"

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