[Fireredburn1]

What is the mechanism for this reaction?



Here's my attempt. My guess is that formaldehyde will react with one of the amine group to form an imine group. But here's where I am stuck at. It seems almost impossible to insert an oxygen atom into the final product if I were to go by an imine intermediate.

There oxygen atom must have been from the formaldehyde but it is obvious that isn't from an nucleophilic addition.

Help will be greatly appreciated!

[Hunter2]

Both amine groups build Aminomethanol.  -NHR + H₂CO => -NHR-CH₂-OH

Both groups eliminate water and build the ether.

[Fireredburn1]

Both amine groups build Aminomethanol.  -NHR + H₂CO => -NHR-CH₂-OH

Both groups eliminate water and build the ether.

How did I not realise that? thank you so much! but why would an imine not be formed instead?

[Hunter2]

I think you will not have 100% yield side reaction can be the imine. But the double bond of imine is easily to open again. Maybe it will produced in between.

[orgopete]

An imine (or iminium ion) is an intermediate. Addition of the oxygen from the aminomethyl group to the imine is the mechanism for the cyclic ether formation. Imines are reversible.