A solution of the product of Example 111-4 in 1,2-dichloroethane (1325 mL) was treated with triethylamine (37.5 mL, 269 mmol, 1.25 equivalents) and N,N-disuccinimidyl carbonate (68.9 g, 269 mmol, 1.25 eq). The reaction mixture was stirred at 20° C. overnight, washed with 10% Na2CO3 (2×1.5 L). The aqueous was back-extracted with dichloromethane (600 mL). The organics were combined and washed with 1.5 L of brine. The organic layer was concentrated to yield 76.8 gm of crude material. 1H NMR (CDCl3): δ 7.15-7.3(m, 5H), 4.25-4.4(m, 3H), 3.75(m, 1H), 3.67(residual dichloroethane), 3.48(m, 1H), 3.1(m, 2H), 1.4(s, 9H), 1.0(s, 9H).
