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Topic: displacement of mesylate by dimethylamine gas  (Read 3298 times)

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Offline ashdv2002

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displacement of mesylate by dimethylamine gas
« on: October 07, 2010, 08:40:01 AM »
We have activated a particular alcohol by mesylation, now we are trying to displace it with dimethylamine gas or 40% Dimethylamine solution.?What will be the best solvent & temperature conditions for the same.

Offline Dan

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Re: displacement of mesylate by dimethylamine gas
« Reply #1 on: October 07, 2010, 09:17:25 AM »
Either solution or gas should be much the same, solution is easier to handle so I'd try that first. Keep the amine in large excess to minimise tetra-alkylammonium salt formation. How hindered is the alcohol? By the way, if it is primary (or achiral secondary) it might be more effective to oxidise to the aldehyde and introduce NMe2 by reductive amination. Altenatively you could displace the mesylate with azide and then reduce the azide with H2/Pd with excess formaldehyde.

R-OMs + HNMe2 -----> R-NMe2 (possible side reaction: R2NMe2+ MsO-)

Alternatives:

R-OH ----> R=O --HNMe2, ([H2, Pd/C] or NaBH3CN) --> R-NMe2

R-OMs --NaN3--> R-N3 ---H2CO, H2, Pd/C ---> R-NMe2
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