Description
Triethyl phosphonoacetate is a reagent for organic synthesis used in the Horner-Wadsworth-Emmons reaction (HWE) or the Horner-Emmons modification. This compound can be added dropwise to sodium methoxide solution to prepare a phosphonate anion. It has an acidic proton that can easily be abstracted by a weak base. When used in an HWE reaction with a carbonyl, the resulting alkene formed is usually the E alkene and is generated with excellent regioselectivity. It can synthesize β-Keto Phosphonates via an acylation reaction of triethyl phosphonoacetate with carboxylic acid chlorides in the presence of magnesium chloride-triethylamine followed by decarbethoxylation. Acylation of triethyl phosphonoacetate using magnesium ethoxide affords acyl phosphonoacetates, which, on treatment with catalytic p-TsOH in water, are converted into 2-aryl-2-oxoalkylphosphonates[1-2].
Chemical Properties
Triethyl phosphonoacetate is Colorless to light yellow liqui
Uses
Triethyl phosphonoacetate is used for Horner-Emmons modification.
Uses
Triethyl phosphonoacetate serves as a reactant used in Horner-Wadsworth-Emmons reactions, Tsuji-Trost type reactions, Intramolecular Heck-type cyclization and isomerizations and Intramolecular aryne-ene reactions. In Horner-Wadsworth-Emmons reaction, it is utilized as a reagent to prepare chiral 2-methylcyclopropanecarboxylic acid from (S)-propylene oxide.
reaction suitability
reaction type: C-C Bond Formation
Synthesis
Triethyl phosphonoacetate was prepared as follows: a dry clean 500 mL coil was heated to 170C, 1000 g (0.7eq.8.16 mol) of compound 1 (boiling point 142-145C at standard atmospheric pressure) was placed in a beater bottle A and diluted with 4000 g of toluene, 1937 g of triethyl phosphite (boiling point 156.6C at standard atmospheric pressure) was taken (1.0eq.11.66mol) was placed in the beater bottle B, 3063g of toluene was added and diluted, the beater was started after the temperature of the coil was stabilized, pump A (toluene solution of triethyl phosphonoacetate): 16.7g/min, pump B (toluene solution of triethyl phosphite): 16.7g/min. Residence time was 15min, and the reaction pressure was 0.5~2.0Mpa. The discharge port was directly connected to a thin film evaporation device, controlling the pressure of 4~1010<2>Pa and temperature of 105~115C. The final product, triethyl phosphonoacetate (boiling point 129~131C800Pa) was obtained as 1701g, with a yield of 93%.
Purification Methods
Purify it by fractional distillation, preferably in vacuo. NMR has P resonance at 19.5 relative to orthophosphate. [Kosolapoff & Powell J Am Chem Soc 68 1103 1946, Kosolapoff & Powell J Am Chem Soc 72 4198 1950, Speziale & Freeman J Org Chem 23 1586 1958, Beilstein 4 IV 3613.]
References
[1] D. Kim, D. Rhie, M. S. Kong. “A New Synthesis of 2-Aryl-2-Oxoalkylphosphonates from Triethyl Phosphonoacetate.” Synthetic Communications 25 1 (1995): 2865–2869.
[2] D. Kim, T. Kim, M. S. Kong. “A Practical Synthesis of β-Keto Phosphonates from Triethyl Phosphonoacetate.” Synthetic Communications 32 1 (1996): 2487–2496.
