Verfahren zur Herstellung von (cis-1,2-Epoxypropyl)-phosphonsäureestern

1,246,206. (Cis 1,2 - epoxypropyl) - phosphonic acid and intermediates therefor. MERCK & CO. Inc. 12 May, 1969 [15 May, 1968], No. 23985/69. Heading C2C. (Cis-1,2-epoxypropyl)-phosphonic acid and its salts and esters are obtained by treating a formyl phosphonate, e.g. a compound in which R is a C 1 -C 5 alkyl, C 2 -C 5 alkenyl, aryl, or aralkyl radical with an ethylide which is substituted at the methylene carbon by an appropriate leaving group, i.e. a compound M#-CH#-CH 3 wherein M+ is the leaving group, e.g. a di-(C 1 -C 5 )- alkoxy phosphinyl, di-(C 1 -C 5 ) alkyl or diaryl sulphonium, tri-(C 1 -C 5 )-alkyl- (or triaryl) - ammonium, di-(C 1 -C 5 )-alkyl sulphoxonium, tri-(C 1 -C 5 )-alkyl phosphonium or triaryl phosphonium cation. The process is suitably conducted in a solvent, e.g. an ether or dimethylsulphoxide, and the ethylide reactant may be prepared in situ in the solvent and the formyl phosphonate then added to the solution. When the products are esters they may be converted to the free (cis-1,2-epoxypropyl)-phosphonic acid, e.g. by hydrolysis with a mineral acid, hydrogenolysis, or treatment with trimethylchlorosilane followed by -aqueous hydrolysis. The phosphonic acid may then be converted to a salt, e.g. an alkali metal or alkaline earth metal salt, especially the calcium or disodium salt, by treatment with an aqueous solution of an appropriate base. Diethyl sulphoxonium ethylide is obtained by reacting diethyl sulphoxide with ethyl iodide in solution at 100-110‹ C. to form triethylsulphoxonium iodide and then treating the latter with sodium methylsulphonyl methylide in dimethyl sulphoxide. Triethylammonium ethylide is obtained by adding tetraethylammonium bromide in ether to an ethereal solution of phenyl lithium at 25‹ C. and decanting the supernatant liquid. Diethylsulphonium ethylide is obtained by reacting diethyl sulphide with ethyl bromide to form triethylsulphonium bromide and then treating the latter with an equivalent of sodium methyl sulphonyl methylide in dimethylsulphoxide.