1,1′-(Azodicarbonyl)dipiperidine (370 mg, 1.5 mmol) was added to the solution of methyl 3-(5-hydroxyindolyl)propanoate (220 mg, 1.0 mmol), as prepared in step g of Example 5, 3-(benzyloxycarbonylamino)propanol (230 mg, 1.1 mmol) and tri-n-butylphosphine (305 mg, 1.5 mmol) in tetrahydrofuran (20 mL). After stirring at ambient temperature overnight, the reaction mixture was concentrated and the residue was purified by flash column chromatography on silica gel (0-2% ethyl acetate in methylene chloride) to give the title compound as an off white solid (310 mg, 76%). 1H-NMR (400 MHz, CDCl3) δ 7.35 (m, 5H), 7.22 (d, J=8.9 Hz, 1H), 7.09 (d, J=3.1 Hz, 1H), 7.07 (d, J=2.1 Hz, 1H), 6.86 (dd, J=8.8, 2.4 Hz, 1H), 6.38 (d, J=2.9 Hz, 1H), 5.11 (br s, 3H), 4.41 (t, J=6.8 Hz, 2H), 4.07 (t, J=5.9 Hz, 2H), 3.66 (s, 3H), 3.44 (q, J=6.3 Hz, 2H), 2.81 (t, J=6.8 Hz, 2H), 2.02 (m, 2H).
