Ethanol → HCID 15914641, compound

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Reaction Steps

Diethyl N-(ethoxycarbonylcarbonyl)aminomethylphosphonate (15.0 g prepared as described in Example 1) in dry dichloromethane (90 ml) was placed in a flask which was sealed with a rubber septum. Trimethylsilyl bromide (28 ml); ca. 3.8 molar proportions was added by syringe through the septum and the mixture stirred for four hours at room temperature. The solution was then evaporated under reduced pressure to give a yellow oil. This was taken up in dry dichloromethane (ca. 100 ml) and treated with ethanol (20 ml) to decompose the intermediate trimethylsilyl ester. The solution was then evaporated under reduced pressure to leave a yellowish semi-solid residue. Trituration of this with ethanol (ca. 8 ml) gave N-(ethoxycarbonylcarbonyl)aminomethylphosphonic acid as a white solid (6.82 g). A sample of acid prepared in this way (40 g) was taken up in ethanol (1500 ml) to give a slightly cloudy solution. To this isopropylamine (10.8 g, one molar proportion) was added dropwise with stirring. When addition was complete, the mixture was stirred for 2 hours and then evaporated under reduced pressure. The remaining viscous brown oil was taken up in warm ethanol (50 ml) and the solution diluted with ether until slightly cloudy. On standing, a white solid separated. This was collected and washed with ethanol (ca. 50 ml) and then ether, giving Compound no. 6 Table 1 (48.7 g). A sample recrystallised from ethanol (50 ml) plus water (3 ml) had a melting point of 158°-160°.

Provenance & Evidence