Scheme 2: Reagents and conditions: (i) benzyl bromide, K2CO3, acetone, reflux, 7 h; (ii) (a) p-anisoyl chloride or (b) benzoyl chloride, K2CO3, acetone, reflux, 7 h; (iii) DIEA, HOBt.H2O, EDC.HCl, acetic acid, dry THF, rt, 18 h; (iv) Methyl iodide, NaH, dry THF, rt, 72 h; (v) HCl/isopropanol [5-6 N], rt, 2 h.