Example 180
Compound 33 (30.2 mg, 0.056 mmol), EDC (25.0 mg, 0.130 mmol) and pentafluorophenol (11 mg, 0.060 mmol) were dissolved in dichloromethane (4 mL) and the reaction was stirred overnight at room temperature, then concentrated to dryness to give compound perfluorophenyl 2-((1R,3R)-1-acetoxy-3-((2S,3 S)—N,3-dimethyl-2-((R)-1-methylpiperidine-2-carboxamido)pentanamido)-4-methylpentyl)thiazole-4-carboxylate, 33a, which was dissolved in 4 mL of DMA, and a solution of compound 165a (160 mg, 0.213 mmol) in 3 mL of DMA and DIPEA (26.8 μL, 0.154 mmol) were added. The reaction was stirred at room temperature overnight and then concentrated. The residue was diluted with 1 mL of acetonitrile and purified by reverse phase HPLC with a gradient of MeCN/H2O (10% MeCN to 40% MeCN in 45 min, d2 cm×L25 cm, C-18 column, 8 ml/min) to afford compound 720 (133.1 mg, 48% yield). ESI: m/z: calcd for C61H93N10O17S [M+H]+: 1269.6442, found 1282.6630.
