DIETHYL CYCLOHEXYLAMINOVINYL PHOSPHATE

Uses

Diethyl β-(Cyclohexylimino)ethylphosphonate is used as a reagent for formylalkenation at carbonyl centers.^[1]

Preparation

Preparative Methods of Diethyl β-(Cyclohexylimino)ethylphosphonate: (EtO)2CHCH2P(O)(OEt)2 is prepared by reaction of Triethyl Phosphite with BrCH2CH(OEt)2. Acetal hydrolysis affords diethyl formylmethylphosphonate, which is combined with an equimolar quantity of cyclohexylamine in MeOH. The product is isolated by fractional distillation in the presence of K2CO3, to prevent acid-catalyzed dimerization, and at reduced pressure, followed by crystallization from cold pentane.^[1b] Yields are 65-75%. A modified procedure for imine formation uses MeCN as solvent with isolation of product from Et2O at -40 °C to afford white crystalline material in 70% yield.^[2]

storage

Crystalline material of Diethyl β-(Cyclohexylimino)ethylphosphonate is stable for several months when stored under anhydrous conditions at 0 °C.

Purification Methods

Purification of Diethyl β-(Cyclohexylimino)ethylphosphonate: distillation at reduced pressure. Crystallization from pentane at 0 °C.

References

1. (a) Nagata, W.; Hayase, Y. TL 1968, 4359. (b) Nagata, W.; Wakabayashi, T.; Hayase, Y. OS 1973, 53, 44. (c) Nagata, W.; Wakabayashi, T.; Hayase, Y. OS 1973, 53, 104. (d) Nagata, W.; Hayase, Y. JCS(C) 1969, 460.
2. Farnum, D. G.; Ghandi, M.; Raghu, S.; Reitz, T. JOC 1982, 47, 2598.