Carbon tetrabromide → dimethyl N-(5-isopropyl-2-morpholinophenyl)phosphoramidate

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Reaction Steps

To a stirred solution of 10 ml. of methylene dichloride, 7 ml. of 20% aqueous sodium hydroxide, 3 g. of tetrabromomethane, and 0.2 g. of triethylbenzylammonium chloride was slowly added a solution of 4.0 g. (0.018 moles) of 4-(2-amino-4-isopropylphenyl)morpholine and 2.0 g. of dimethylphosphite dissolved in about 20 ml. of methylene dichloride. The reaction was exothermic and cooling by an ice bath was required. After stirring at ambient temperature for 18 hours, GC analysis indicated the reaction was about 30% complete. Accordingly, a 10% excess of the dimethylphosphite (0.2 g.) and an additional 0.3 g. of tetrabromomethane was added and stirring of the reaction mixture continued overnight. The mixture was then poured into an ice-water solution and the methylene dichloride layer separated. The aqueous layer was extracted twice with methylene dichloride and the combined methylene dichloride phases were rinsed thrice with water. After drying over anhydrous sodium sulfate, the methylene dichloride solution was filtered and evaporated under reduced pressure. The residue was eluted through a silica gel column using 99.5% methylene dichloride and 0.5% methanol to separate the product which was isolated from the solvent as a tan solid (2.2 g.; 37% yield); melting point 97°-98° C.

Provenance & Evidence