Reagents and conditions:
(i)
HATU or dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), N,N-dimethylformamide (DMF), 0 °C—rt,
18 h; (ii) 5FU, DABCO (cat.), DMF, rt—40 °C, 1–24
h; (iii) DABCO, DMF, 0 °C, 1.5 h; (iv) 2 M NaOH (aq), tetrahydrofuran
(THF), rt, 30 min; (v) 4-nitrophenol, DCC, DMAP, DMF, 5 h, rt; (vi)
1-(2-(2-methoxyethoxy)ethoxy)-4-tosylate, K2CO3, DMF, 80 °C, 3 h; (vii) H2, Pd/C (10% wt), MeOH/dichloromethane
(DCM), 40 °C 21 h; (viii) propiolic acid, HATU, DMAP, DMF, 0
°C—rt, 18 h; (ix) 5FU, DABCO, DMF, 40 °C, 40 h; (x)
bis(trimethylsilyl)ethylene, AlCl3, DCM, 0 °C—rt,
18 h; (xi) tetra-n-butylammonium fluoride (TBAF),
MeOH, −78 °C, 1 h; (xii) 5FU, DABCO, DMF, 40 °C,
30 min.