Sodium cyanoborohydride in methanol at 0°C with a catalytic amount of acetic acid works in most cases.

Cyanoborohydride would be the first thing to try, per Jan's suggestion ... what have you tried, and what's gone wrong? (No reaction, wrong products, tar?)

I do not know the exact structure of your compounds. We have a similar problem. Borate formation with my compound, this borate can't be removed by regular work up procedure. Please see Adv. Synth. Catal. 2009, 351, 3089-309.

I am working on very small quantity (it would be my final step). I am trying so far Sodium Borohydride (same procedure as a patent that shows similar molecules to mine -analogues of tranylcypromine) but it does not work. Jan Hullaert: do you use molecular sieves by chance as well? for how long the reaction? do you see an imine formation?Thank you very much!

The problem with sodium borohydride is that it reduces your aldehyde before the imine is formed, in case you don't wait for a couple of hours to add the sodiumborohydride. Be careful with procedures coming from patents.

Mol. sieves wil indeed help the imine formation. I do not have acces to the details of the procedure I followed.

Another procedure that should work is sodium triacetoxyborohydride, with 3 equiv. acetic acid, mol sieves in acetonitrile. Starting at 0°C, if nothing happens raising the temperature even to reflux should do the trick.

Maybe you should first try it on a test substrate, but I do not think any of these conditions would ruin the starting material.

Good Luck!

Thanks Jan Hullaert, I will try your the procedure you suggested!

Your sodium borohydride procedure will also work but first u have to react your aldehyde and amine for some time in solvent and then gradually add solid sodium borodhydride slowly and after addition check conversion and workup with min. amount of water.