This reaction was carried out in a dry flask maintained under argon atmosphere by mixing 1.15 g of l-proline, 1.32 g of
potassium carbonate and 20 ml of methanol.
To this mixture,2.5 g of ethyl chloroformate was slowly added and, after this, the system was refrigerated until 0 ◦C.
The solution obtained was shaken during 2 h and then deionized water and saturated solution of NaHCO3 were added.
At this condition, the intermediate carbamate-ester (substance C) was formed and extracted with three portions of 15 ml of ethyl acetate.
These portions were dried with anhydrous Na2SO4, and the yellow liquid obtained was distilled at low pressure being obtained 1.90 g of an uncolored liquid of C with a boiling point of 93 ◦C, that corresponds to a reaction yield of 95%.
The identification of the reaction product was performed by infrared