[ashdv2002]

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.

[Dan]

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