Sodium Hydroxide → 4-(3-(3-(Tert-butoxycarbonylamino)-1-hydroxypropyl)phenoxy)butanoic acid

To the ester 130 (2.3 g, 6.0 mmol) in THF (80 mL) and MeOH (20 mL) was added NaOH solution (8 mL, 2N). The resulting mixture was stirred at room temperature for overnight following which the solvent was removed under reduced pressure and pH adjusted to 6 by the addition of cold dilute HCl. This was then extracted with DCM. The organic layer was washed with water, dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to give 4-(3-(3-(tert-butoxycarbonylamino)-1-hydroxypropyl)phenoxy)butanoic acid (131). The product was directly utilized for the next transformation. Yield (1.94 g, 91%): 1H NMR (400 MHz, CDCl3) δ 7.18-7.22 (m, 1H), 6.84-6.90 (m, 2H), 6.77 (dd, J=7.6, 1.6 Hz, 1H), 5.18 (bs, 1H), 4.48-4.53 (m, 1H), 3.96 (t, J=6.4 Hz, 2H), 2.93-2.99 (m, 2H), 2.38 (t, J=7.4 Hz, 2H), 1.90-1.96 (m, 2H), 1.64-1.71 (m, 2H), 1.45 (s, 9H).