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Topic: Reduction of Benzil to meso-hydrobenzoin  (Read 12827 times)

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Offline MagicAcid

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Reduction of Benzil to meso-hydrobenzoin
« on: March 27, 2009, 03:19:57 PM »
In a recent organic chemistry lab, I attempted to reduce benzil to meso-hydrobenzoin with sodium borohydride and eventually water (a rather simple undergrad lab).  I understand most of the chemistry behind the reaction, but I find myself wondering why the meso form of hydrobenzoin predominates.  I believe the formation of the first asymmetric center affects the production of the second, but I cannot seem to come up with a mechanism that explains the results.  According to some sources, there is a cyclic borate ester intermediate during the reaction, but I do not understand how that intermediate actually forms.  Any help at all would be greatly appreciated.

Offline azmanam

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Re: Reduction of Benzil to meso-hydrobenzoin
« Reply #1 on: March 27, 2009, 03:41:17 PM »
my guess is this is probably a chelation controlled reduction (as opposed to felkin-ahn selectivity), but I didn't draw out the model

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