Phosphorus trichloride → 2-Hydroxymethyl-5,7-dimethyl-3-(2-methylsulfamoyl-phenyl)-4-oxo-3,4-dihydroquinazoline-6-carboxylic Acid Butyl Ester

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Reaction Steps

Preparation of 2-Benzyloxymethyl-5,7-dimethyl-3-(2-methylsulfamoyl-phenyl)-4-oxo-3,4-dihydro-quinazoline-6-carboxylic acid ethyl ester: To a mechanically-stirred suspension of 4-(Benzyloxyacetyl)amino-2,6-dimethyl-isophthalic acid 1-ethyl ester (27 g, 0.07 mol), 2-amino-N-methyl-benzenesulfonamide (13 g, 0.07 mol) and anhydrous toluene (500 mL) in a three-necked round bottom flask is added phosphorus trichloride (51 mL, 0.56 mol) via an addition funnel. The reaction mixture is stirred at room temperature for 5 minutes and then heated to reflux. After 45 minutes LCMS analysis indicates that the reaction is complete. The suspension is cooled to room temperature and the solution phase is decanted from the solid material. The solution and solid material are worked-up separately. The toluene solution is partitioned between ethyl acetate and saturated aqueous NaHCO3 solution with vigorous stirring to give a clear biphasic solution. The organic and aqueous phases are separated and the aqueous phase is extracted (×2) with ethyl acetate. The organic phases are combined, dried over anhydrous Na2SO4, and evaporated in vacuo to give an orange oil. Similarly, the solid material is stirred, vigorously with ethyl acetate and saturated aqueous NaHCO3 solution to give a clear biphasic solution. The organic and aqueous phases are separated and the aqueous phase is extracted (×2) with ethyl acetate. The organic phases are combined, dried over anhydrous Na2SO4, and evaporated in vacuo to give an orange oil. Trituration of the orange oil with diethyl ether provides a yellow solid, which is removed by filtration, washed with diethyl ether and air-dried to provide the title compound.

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