Oven-dried 2L flask with a large egg-shaped stirbar was flushed with Ar and 95% sodium hydride 3.484g (138mmol) was quickly added (fire hazard!) followed by anh. THF 0.5L. Neat L-alaninol 9.865g (131.3 mmol) was added over 5 min (H2 evolution) without cooling. The obtained slurry of sodium aminoalcoholate was stirred under Ar for 45 min, then Ethyl chloroacetate 16.177g (132 mmol) was added. The mixture was stirred for 30 min at ambient temperature, then refluxed for 3 hours. The flask was cooled on ice bath, LAH 12g was carefully added in several portions (3x1g, then 3x3g) with cooling. 15 min after complete addition, the flask was placed on oil bath 95-100C and refluxed for 3 hours 30 min.The reaction mixture was cooled on ice bath, carefully quenched by dropwise addition of water 12 mL, diluted with THF (300mL), 15% NaOH 36 mL was added and the mixture was stirred overnight (16 hours). The solids were removed by filtration (and washed with additional THF) and the filtrates were carefully concentrated (ambient water bath, 60 Torr) The residue was distilled at normal pressure under Ar. After a smallTHF fraction, the pure product distilled, b.p. 136-8C (oil bath was 160-200C). Y=6.513g (49% th) of a clear liquid.
1H(CDCl3, 400MHz): 3.777 (br m, 1H), 3.732 (dd, 11.0Hz, 2.7Hz, 1H), 3.465 (app td, 11.4Hz(t), 2.3Hz(d), 1H), 3.083 (app t, 10.1Hz, 1H), 2.983(app td, 11.7Hz(t), 3.5Hz(d), 1H), 2.901(m, 1H), 2.805(br m, 1H), 0.958 (d, 6.3Hz, 3H); 13C-NMR(CDCl3, 100MHz): 73.99, 67.45, 50.62, 46.52, 18.11
In humid places like Florida, oil-free sodium hydride should be avoided because of its risk of self-ignition. It is helpful to use a dry test tube with a septa, as a disposable reagent container when weighing flammable powder reagents (NaH, LAH, etc.). The material in test tube is dumped into Ar-filled flask in a single portion. For LAH gradual addition, it is convenient to pre-weight several separate dump-portions and keep them under septa in a dessicator.