Diethyl 5-hydantoylphosphonate → Ethyl 4-[3-[(2,4-dioxoimidazolidin-5-ylidene)methyl]-4-nitrophenoxy]butanoate

Participants

Reaction Steps

Sodium (4.92 g, 0.21 g atom) was dissolved in absolute ethanol (600 mL) and diethyl 2,4-dioxoimidazolidine-5-phosphonate (50.5 g, 0.21 mole) added. After 10 minutes, a solution of ethyl 4-(3-formyl-4-nitrophenoxy)butanoate (50.0 g, 0.18 mole) in ethanol (100 mL) was added in one portion. The mixture was stirred for 2 hours, concentrated in vacuo to about 250 mL and diluted with water. After 20 minutes the precipitate was filtered off. Two further crops were subsequently collected from mother liquors. Combined solids were dried in vacuo over P2O5 to afford ethyl 4-[3-[(2,4-dioxoimidazolidin-5-ylidene)methyl]-4-nitrophenoxy]butanoate (61.3 g, 95%) which by NMR was a 4:1 mixture of geometrical isomers. An analytical sample of the major isomer was obtained by crystallization from aqueous ethanol and had m.p. 131°-134° C.

Provenance & Evidence