Phosgene cyclization of aminoalcohol

Phosgene (20% solution in toluene) (46.2 mL, 87.0 mmol) One 1 L round-bottomed flask with magnetic stir bar Methanol (lOOmL) 

Silica gel (Whatman, bulk 230 00 mesh), height 8 cm One filter flask, lOOOmL One addition funnel, 50 mL Water aspirator 

Aminoalcohol 5 (17.4 g, 62.0 mmol) and sodium bicarbonate (30.0g, 360.0mmol) were suspended in methylene chloride (300 mL) at 0 °C under nitrogen. 

After 6 h of stirring at room temperature, the reaction was assessed to be complete by TLC (the product has an Rf of about 0.5 in ethyl acetate while the starting material remains on the baseline), so the mixture was opened to air. 

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