PREPARATION OF (CIS-1,2-EPOXYPROPYL)PHOSPHORIC ACID AND DERIVATIVES THEREOF AND INTERMIDIATES THEREFOR

1,240,048. (Cis - 1,2 - epoxypropyl)phosphonic acid derivatives. MERCK & CO. Inc. 12 May, 1969 [15 May, 1968], No. 23982/69. Heading C2C. The invention comprises cis compounds of the formula in which X is a halogen atom or a mercapto radical and each R is a hydrogen atom or a substituted or unsubstituted univalent hydrocarbyl or heterocyclic radical or an equivalent of an organic or inorganic salt-forming cation. The compounds in which X is halogen may be obtained by epoxidizing e.g. with an organic per-acid a cis compound of the formula wherein Z is halogen, the latter compound being obtainable by reacting a compound of the formula with an iodobenzene dihalide. The compounds (I) in which X is a mercapto radical are prepared by reacting a compound of the formula in which Z is a halogen atom with a hydrosulphide ion. The compounds in which X is a mercapto radical may be desulphurized e.g. by treatment in solution with Raney-nickel, - copper, -cobalt or -iron or with nickel boride, alkaline sodium plumbite, sodium in liquid ammonia, lithium in an alkylamine or aluminium amalgam, to form a cis compound of the formula With some desulphurizing agents, e.g. Raney nickel or Raney cobalt or aluminium amalgam both desulphurization and ester cleavage may occur when the starting material is a mono- or di-ester. The cis compounds (IV) may also be obtained by dehalogenating and hydrogenating a cis compound (I) in which X is halogen, the process being suitably effected by using hydrogen and a hydrogenation catalyst such as a noble metal catalyst generally in a solvent under hydrogen pressure and in the presence of a base such as triethylamine or sodium acetate. The hydrosulphide ion used in the conversion of the (cis - 1,2 - dihalo - 1,2 - epoxypropyl)phosphonic acid compound (II) may suitably be obtained by dissolving an alkali metal hydrosulphide in an alcohol, e.g. ethanol or methanol. When the product of Formula IV is an ester it may be converted to the free acid or salts thereof. The products (IV) are racemic mixtures which can be resolved into their optically active forms.