GENERAL STEPS: A mixture of L-alanine (2.5 g, 28 mmol), formaldehyde (8.4 g, 37 wt.%), 1N HCl (30 mL), and 10% Pd/C (500 mg) in methanol (30 mL) was subjected to a hydrogen atmosphere (50 psi), and the reaction was stirred for 5 hours. Upon completion of the reaction, the mixture was filtered through diatomaceous earth (Celite) and the filtrate was concentrated under vacuum to afford an oily salt of (S)-2-(dimethylamino)propionic acid, which was solidified upon vacuum standing (4.4 g; yield higher than the theoretical value). The resulting product was used in subsequent steps without further purification.1H NMR (DMSO-d6, δ= 2.5, 500 MHz) data were as follows: δ 12.1 (br s, 1H), 4.06 (q, J = 7.4 Hz, 1H), 2.76 (s, 6H), 1.46 (d, J = 7.3 Hz, 3H).
