A method for preparing 4-(hydroxymethylphosphinyl)-2-oxobutanoic acid, comprising the following steps: a) mixing 3-chloropropionyl chloride, a first solvent, trimethylsilyl cyanide and cyanide salt, performing a substitution reaction to obtain a material solution containing 4-chloro-2-oxobutyronitrile, then performing distillation under reduced pressure, and performing separation to obtain 4-chloro-2-oxobutyronitrile intermediate; b) subjecting the 4-chloro-2-oxobutyronitrile intermediate obtained in step a) and methyl phosphonite diester to Arbuzov reaction in a second solvent in the presence of cuprous iodide to obtain a material solution of (3-cyano-3-oxopropyl) methyl phosphinate, and performing purification to obtain crude (3-cyano-3-oxopropyl) methyl phosphinate; c) mixing the obtained crude (3-cyano-3-oxopropyl)methyl phosphinate with hydrochloric acid, performing hydrolysis reaction, and then performing purification treatment to obtain 4-(hydroxymethylphosphinyl)-2-oxobutanoic acid. This preparation method can prepare 4-(hydroxymethylphosphinyl)-2-oxobutanoic acid with high yield, and the reaction conditions are mild, the operation is simple, the production cost is low, and it is easy to realize industrialization.

An object of the present invention is to provide an aldehyde compound and an ester compound that both have difluoro at the -position, a double bond or epoxy at the -position, and a disubstituted alkene at the -position. Provided are difluoroaldehyde, epoxy, and derivatives thereof.

An object of the present invention is to provide an aldehyde compound and an ester compound that both have difluoro at the -position, a double bond or epoxy at the -position, and a disubstituted alkene at the -position. Provided are difluoroaldehyde, epoxy, and derivatives thereof.