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With sodium carbonate; In 1,4-dioxane; water; at 20℃; for 12h;
Step 3a: To a stirred solution of compound 1a (5.0 g, 30.6 mmol) in 1,4-Dioxane (50 mL), Sodium carbonate (8.12 g, 76.5 mmol, dissolved in 10 mL water) and (Boc)2O (9.98 mL, 45.7 mmol) were added and stirred at room temperature for 12 h. The progress of reaction was monitored by TLC. The reaction mass was partitioned between diethyl ether and water. Then aqueous layer was made acidic (pH=3) by 3N HCl solution and was extracted with DCM (2×200 mL). Organic layer was washed with water, brine, dried over Na2SO4 and evaporated under reduced pressure to yield 50 g of pure 3a (Yield: 62.1%). LCMS: 263.0 (M+H)+
62.1%
With sodium carbonate; In 1,4-dioxane; water; at 20℃; for 12h;
To a stirred solution of compound la (5.0 g, 30.6 mmol) in 1,4-Dioxane (50 mL), Sodium carbonate (8.12 g, 76.5 mmol, dissolved in 10 mL water) and (Boc)20 (9.98 mL, 45.7 mmol) were added and stirred at room temperature for 12 h. The progress ofreaction was monitored by TLC. The reaction mass was partitioned between diethyl ether and water. Then aqueous layer was made acidic (pH = 3) by 3N HC1 solution and was extracted with DCM (2 x 200 mL). Organic layer was washed with water, brine, dried over Na2504 and evaporated under reduced pressure to yield 50 g of pure 3a (Yield:62.1%). LCMS: 263.0 (M+H).