General procedure for the synthesis of Boc-11-aminoundecanoic acid from 11-aminoundecanoic acid and di-tert-butyl dicarbonate: 160 g of 11-aminoundecanoic acid, 2 liters of dioxane, 1.3 liters of distilled water, 208 g of sodium carbonate, and 173 g of di-tert-butyl dicarbonate were added sequentially to a 4-liter three-necked flask in a unit equipped with a mechanical stirrer and reflux condenser. The reaction mixture was heated to boiling point and the reaction was continued with stirring for 16 hours to obtain a clarified solution. Upon completion of the reaction, the mixture was cooled to 20 °C and subsequently poured into 800 g of ice and the pH was adjusted to 3-4 with 4 N hydrochloric acid, at which point a white precipitate was produced. The precipitate was separated by filtration, washed with 300 cm3 of water and then dried under reduced pressure at 20 °C (20 mm Hg, 2.7 kPa) to give 232 g of N-(tert-butoxycarbonyl)-11-aminoundecanoic acid in 95% yield. The melting point of the product (68°C) is in agreement with that reported in the literature J. Org. Chem. 1997,1987.Chem., 41,1350 (1976).
