General procedure: preparation of mono-Boc-protected 1,7-diaminoheptane. Di-tert-butyl dicarbonate (Boc2O, 0.500 g, 2.291 mmol) was dissolved in chloroform (CHCl3, 10 mL) and the solution was added slowly and dropwise to a solution of 1,7-diaminoheptane (11.45 mmol) in chloroform (50 mL). The reaction mixture was stirred at room temperature for 24 hours. Subsequently, the reaction solution was concentrated and purified by fast column chromatography (silica gel, SiO2) using a gradient elution (0-10% MeOH) with chloroform/methanol (MeOH) containing 1% triethylamine (Et3N) to afford mono-Boc-protected 1,7-diaminoheptane ((tert-butyl (7-aminoheptyl)carbamate) as a colorless semi-solid (0.473 g, 90% yield ).1H NMR (CDCl3) δ: 4.52 (broad single peak, 1H), 3.12 (quadruple peak, J = 6.2 Hz, 2H), 2.70 (triple peak, J = 6.8 Hz, 2H), 1.43-1.23 (multiple peaks, 19H).
