PMGB

To a suspension of the amine HCl salt (0.0437 mol) in 60 mL acetonitrile cooled by an ice-bath was added N,N-diisopropylethylamine (DIPEA) (0.11 mol). Aliphatic bromide (0.0437 mol) was added and the resulting mixture was stirred at room temperature for overnight (12 h). The solution became clear in the morning. The solvent was evaporated, residue was diluted with 50 mL dichloromethane, washed with 50 mL water, dried (MgSO₄) and evaporated to give the corresponding N-alkylated product which was purified by silica gel column chromatography using a gradient of hexane and ethyl acetate (colorless oil, 95% yield).

Reference: Moore, J. L.; Taylor, S. M.; Soloshonok, V. A. Arkivoc 2005, vi, 287-292.

Note: For unreactive long chain aliphatic bromides the reaction has to be heated at reflux for overnight (12 h) to get the product.

N-Benzylation:

To the amine HCl salt (0.044 mol) in 75 mL acetonitrile cooled in an ice-bath was added N,N-diisopropylethylamine (DIPEA)  (0.088 mol) followed by benzyl bromide (0.044 mol). The mixture was stirred at room temperature for overnight (12 h). The solvent was evaporated, the residue was diluted with 100 mL dichloromethane, washed with 100 mL water, dried (MgSO₄) and evaporated to give the corresponding N-benzylated product in quantitative yield.