Triisopropyl phosphite → 5-Benzyloxy-4-diisopropylphosphonomethyl-2-formylamino-pent-3-enoic acid ethyl ester

Beteiligte Stoffe

Reaktionsschritte

1.0 g (3.25 mmol) of 5-benzyloxy-2-formylamino-3-hydroxy-4-methylene-pentanoic acid ethyl ester are suspended in 30 ml of 1,2-dichloroethane, and 0.38 ml (4.9 mmol) of thionyl chloride is added dropwise at room temperature. After 45 minutes, 20 ml of water are added to the yellow solution, and the mixture is stirred vigorously for 15 minutes. The organic phase is separated off, washed with saturated sodium chloride solution, dried over Na2SO4, filtered and concentrated by evaporation. 5-benzyloxy-4-bromomethyl-2-formylamino-pent-3-enoic acid ethyl ester is obtained in the form of a yellowish oil which is reacted further in the crude state. 1.14 g (3.1 mmol) of 5-benzyloxy-4-bromomethyl-2-formylamino-pent-3-enoic acid ethyl ester and 10 ml (38.5 mmol) of triisopropyl phosphite (95%) are heated to 80° C. and stirred under a pressure of approximately 130 mbar for 31/2 hours. The excess triisopropyl phosphite is distilled off and the residue is purified by chromatography on silica gel with ethyl acetate. 5-benzyloxy-4-diisopropylphosphonomethyl-2-formylamino-pent-3-enoic acid ethyl ester is obtained in the form of a yellowish oil.

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