solution of 2.18 g of di-tert-butyl dicarbonate (10 mmol) in dry CH, Cl,(50 mL) were added 1.5 g of L-valinamide hydrochloride (10 mmol) and 2.1 g of triethylamine (20 mmol). The reaction mixture was refluxed for 3 h. Triethylamine salts were extracted twice by 10 mL of water, and the organic phase was evaporated in vacuo to give 1.9 g (90% yield) of an oily residue which readily crystallized upon standing at room temperature: Rf 0.03; mp 157" C; ...
