By using an analogous procedure to that described for Reference Example 13, Fmoc-11-aminoundecanoic acid (2 g, 4.7 mmol), hydroxybenzotriazole (639 mg, 4.7 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (906 mg, 4.7 mmol), 1-amino-3,3-diethoxypropane (662 gm, 4.5 mmol) and N,N-diisopropylethylamine (0.834 ml, 4.7 mmol) were reacted in anhydrous tetrahydrofuran (30 ml) at room temperature for 16 hours. Purification by chromatography (flash column, silica gel, 50-80% ethyl acetate in hexanes then 10% methanol in methylene chloride) provided 9H-fluoren-9-ylmethyl 11-[(3,3-diethoxypropyl)amino]-11-oxoundecyl-carbamate (560 mg, 23%) as a white solid.
