You can use NaCNBH3 after reacting with aldehyde. Or NiCl2 with NaCNBH3. However, the simplest option would be to react amine with methyl iodide. But you might get dimethyl amine derivative, as the intermediate secondary amine will be more reaction for second substitution reaction.

Add the aldehyde (37%), 5 quiv. will be OK; AcOH 2-3 equiv. and NaCNBH3; leave the reaction (in EtOH) overnigth. You may achieve better results by using MgSO4 instead of NaCNBH3 and after leaving your reaction overnigth (formation of the imine/iminium ion) add the NaCNBH3. Please chech the classical paper by Borch and Dupont Durst.

Dr. Oommen Oommen : thank you very much.. Dr. Teodoro Kaufman : does the reaction required dry condition? because from what i had read, the reaction usually perform using anhydrous solvent..

You dont require dry conditions. I have done reductive amination in water as solvent. Good Luck

Imines are generally unstable. if you are doing reaction in water, set the pH of reaction to 5.5 and use aniline as catalyst.

Classic paper on the subject, employs NaCNBH3:

J. Org. Chem., 1972, 37 (No. 10),1673-1674

Dr maria, if i have amine salt to react with formaldehyde, what should i do. Your suggestion is good for free amine or it can also be applied to amine salt?

Thanks Dr Maria Vale