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Re: ORGLIST: NaH reaction

From: vinutha hanumaiah <vinutha.bl>
Subject: Re: ORGLIST: NaH reaction
Date: Thu, 28 Jun 2012 11:52:29 +0530
Thanks Andrew,
 
DMF problem is solved by FCC using long run of solvents.
Am doing a library like series in which I have used various phenols, but I had no issues with 2-fluoro/methyl, 3-chloro/fluoro/methyl, 4-chloro/fluoro/methyl. Am facing problem only with 2-chloro and expected that the anion was not formed and hence asked some help. Will try by KOH as BuLi or LDA is not used in the moities. Meanwhile have got some ideas like warming the reaction to help in generation of anion and then cool n add my pyridine.. will keep updated about this.
 
Thanks,
Thanu
On Thu, Jun 28, 2012 at 12:04 AM, Andrew Molder <andrew.molder> wrote:

Hydride ion is very stubborn about solubility. You may want to consider trying hydrides with different counter ions .Complexation of your counter ion can change your stereochem. 

Also what about hunig's base BuLi LDA, KOH, etc...? 

Btw did you solve your dmf issues?  I came across the dmf azeotrope I was trying  remember.  Dmf and xylene azeotrope and there is a ton of lit. on it.

On Jun 27, 2012 1:12 PM, "vinutha hanumaiah" <vinutha.bl> wrote:
Hi all,
 
Am doing a regioselective reaction with  2- chlorophenol and a substituted pyridine in DMF.  It seems the phenol is not deprotonated completely in the reaction ending up with less yield. Is it possible to heat the reaction mixture? I have never done heating with NaH. Please can anyone suggest me anyother strong base for deprotonation of phenol or suggest ideas to improve yeilds?
 
Thanks, 
Thanu 

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