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Author Topic: Problem of the Week 07/20/09  (Read 2172 times)

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azmanam

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Problem of the Week 07/20/09
« on: July 20, 2009, 01:13:55 AM »

QUESTION: Explain the stereochemical results for the following transformation
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Dan

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Re: Problem of the Week 07/20/09
« Reply #1 on: July 20, 2009, 01:25:54 AM »

Initially SN2 displacement of mesylate by iodide, then SN2 displacement of that iodide by iodide (eventually) racemises the system?
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azmanam

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Re: Problem of the Week 07/20/09
« Reply #2 on: July 20, 2009, 09:41:29 AM »

Yup.  Two quick ones in a row... I guess I'll have to start making them harder :) 

Iodide is a great nucleophile and a great leaving group.  Initial formation of the optically pure iodide is soon attacked by the good nucleophile I- to liberate the good leaving group I- to give the iodide with the opposite configuration.  Repeated attack of I- to liberate I- eventually provides the racemate.  No SN1 mechanism is proposed.

I've updated the LAH reduction with a different focus.  Take a look at that if you want another challenge this week. http://www.chemicalforums.com/index.php?topic=33985.0
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