The resulting residue was purified using a gradient of 0 to 25% EtOAc/hexanes on silica gel to yield 8 (colorless oil, 3.4 g, 8.82 mmol, 75% yield). A 100 mL round-bottom flask was charged with a stir bar, 8 (3.4 g, 8.8 mmol, 1 equiv.), and MeOH (20 mL). The reaction flask was cooled to 0 °C using an ice-water bath, and K2CO3 (1.5 g, 10.9 mmol, 1.2 equiv.) was added in one bolus. The reaction mixture was warmed to room temperature over a period of 5 hours. Then, the reaction was quenched with a saturated aqueous solution of NH4Cl (20 mL), and the methanol was removed under reduced pressure. The mixture was transferred to a separatory funnel, further diluted with water (20 mL), and the aqueous layer was extracted with EtOAc (2 x 20 mL). The organic layers were collected, dried over MgSO4, and concentrated under reduced pressure. The resulting residue was purified using a gradient of 0 to 35% EtOAc/hexanes on silica gel to yield 9 (colorless oil, 1.9 g, 6.8 mmol, 77% yield). A 250 mL round-bottom flask was charged with a stir bar, 9 (1.4 g, 4.98 mmol, 1 equiv.), Pd(PhCN)2Cl2 (0.282 g, 0.73 mmol, 0.15 equiv.), Cu(OAc)2 (0.890 g, 4.9 mmol, 1 equiv.), Fmoc-Gly-OH (1.4 g, 4.7 mmol, 1 equiv.), molecular sieves (4Ȧ, 725 mg (5 mg/mL of solvent)), and DMSO (145 mL, final concentration: 0.034 M). The reaction vessel was evacuated and backfilled with O2 gas three times. Then, it was submerged in an oil bath preheated to 60 °C and kept at this temperature under a balloon of O2 (~1 atm) for 17 hours. Following this time, the reaction mixture was filtered through a pad of silica gel. The filter cake was further washed with EtOAc. The filtrate was diluted with H2O (500 mL), and the mixture was transferred to a separatory funnel. The aqueous layer was extracted with EtOAc (3 x 200 mL). The organic layers were collected, dried over Na2SO4, and concentrated under reduced pressure. The resulting residue was purified using a gradient of 0 to 35% EtOAc/hexanes on silica gel to yield 10 (crystalline solid, 1.0 g, 3.58 mmol, 72% yield). A 50 mL round-bottom flask was charged with a stir bar, 10 (0.824 g, 2.95 mmol, 1 equiv.), and CH2Cl2 (15 mL). The reaction flask was cooled to 0 °C using an ice-water bath. 2,6-lutidine (1.72 mL, 1.59 g, 14.8 mmol, 5 equiv.) and TBSOTf (2.8 mL, 3.22 g, 12.2 mmol, 4 equiv.) were sequentially added dropwise. The reaction mixture was stirred at 0 °C for 30 minutes. The reaction was then quenched by addition of a saturated aqueous solution of NaHCO3 (15 mL), and the mixture was transferred to a separatory funnel.