Scheme 3. Preparation of BDPA-PEG₅₀₀-DSPE (10). Conditions: (i) PfpOH, EDC, DMAP, CHCl₃, 0 °C to rt, 16 h followed by (ii) DSPE, DIPEA, CHCl₃, reflux, 24 h; (iii) piperidine–DMF 2 : 8, rt, 2 h; (iv) PfpOH, EDC, DMAP, CHCl₃, 0 °C to rt, 16 h followed by (v) 9, DIPEA, CHCl₃, rt, 24 h.