[Cesium-137]

Hi all,
I have been struggling with the yield limiting step in one my synthetic routes. The final product contains an amine which is used as a nucleophile to close a heterocyclic ring. Unfortunetly characterization of the amine intermediate has been nearly impossible as the yield during this last step (before ring closing) has been very low (<10% of theory) and dirty. It appears that aminal formation and hydrolysis are to blame for the low yields. How would one go from an imine salt (C=NMgCl) directly to the amine while avoiding hydrolysis and aminal formation as the desired amine forms? All reagents are anhydrous, and the reaction is done under Ar. Would an excess of MeOH or EtOH be acidic enough to protonate the imine salt forming the imine? Could that imine then be reduced via LiAlH4? or NaBH4? H2/Pd blk or Raney Ni is also an option, but I prefer not to work with pressurized H2. I'm also afraid of using any acid as it would catalyze hydrolysis, and ammonium chloride might favor aminal production...
Any insight would be great! Help me save time and expensive chemicals!

[MissPhosgene]

You are getting a hydrolysis product when your reaction conditions are anhydrous?

You could use NaBH3CN. NaBH4 should bring you directly from iminium to amine as should LiAlH4. Then you won't have to do extra work to get rid of the salt.


What are you working with? 

[Cesium-137]

The hydrolysis product (I think) is created during aqueous workup. Im guessing washing with water hydrolyzes unreduced imines. Also, I would guess the MeOH i've been using is partially wet, as it hasn't been freshly distilled and the sure seal is pretty old. I'm working on a nitrogen/boron heterocyclic ring closure to yield a boronic acid (hopefully stable when cyclized in the ring). Needless to say, working with boron causes major synthetic headaches, especially with amines due to rearrangement and decomposition. The reaction is run in anhydrous THF... If I use NaBH4 I assume I should dissolve it in MeOH first... But that causes the problem of keeping the MeOH anhydrous...