GB1213707A - Phosphorus-containing 1,2,4-oxadiazole derivatives - Google Patents

Abstract

1,213,707. Phosphorus-containing 1,2,4- oxadiazole derivatives and intermediates therefor. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 11 Feb., 1969 [28 March, 1968], No. 14969/68. Headings C2C. [Also in Division A5] The invention comprises novel compounds of the formula wherein X 1 and X 2 , which may be the same or different, are an O or S atom, A is alkylene, R 1 is alkyl, R 2 is alkyl or alkoxy and R 3 is H or an optionally substituted alkyl group, an alkoxycarbonyl group or an optionally N-substituted carbamoyl or amino group. The compounds in which X 1 is an O or S atom and X 2 is a sulphur atom are prepared by reacting a compound of the formula with a salt, e.g. an alkali metal or ammonium salt, of an acid ester of the formula wherein Y 1 is S and Y 2 is O or S and the compounds in which X 1 is O or S and X 2 is O are prepared by reacting a compound of Formula II with a base, e.g. lead hydroxide, to give the corresponding hydroxyalkyl oxadiazole derivative and reacting the latter with a phosphorus halide derivative of the formula wherein Hal is halogen, preferably Cl. The compounds have biocidal properties. The haloalkyl oxadiazoles of Formula II wherein R is an optionally substituted alkyl or alkoxycarbonyl group are obtained by reacting an haloacylamidoxime (Hal.A.C(NH 2 ) = NOH) with an anhydride derived from an acid (R 3 COOH) optionally in the presence of an acid, suitably R 3 COOH or with an acid halide (R 3 COHal) preferably in the presence of a base, e.g. a tertiary amine, to form an acylated haloacyl amidoxime intermediate and then heating the latter to effect ring closure and specific details are given for the production of 3-chloromethyl-5-methyl-1,2,4 oxadiazole and the corresponding 5-propyl and 5-ethoxycarbonyl compounds. Compounds of Formula II wherein R is H may be obtained by a similar method but in which the acid anhydride or halide is replaced by ethyl orthoformate. Compounds of Formula II in which R 3 is an optionally N-substituted carbamoyl or amino group may be obtained from the corresponding compounds in which R 3 is alkoxycarbamyl, e.g. COOC 2 H 5 , or a haloalkyl, e.g. CCl 3 group, by reaction with ammonia or a suitable amine, e.g. dimethylamine or ethylamine, and examples are given for the production of 3- chloromethyl - 5 - carbamoyl - 1,2,4 - oxadiazole and 3-chloromethyl-5-(N-ethylamino)-1,2,4 oxadiazole. 3 - Hydroxymethyl - 5 - methyl - 1,2,4 - oxadiazole is obtained by treating the corresponding 3-chloromethyl compound with lead hydroxide in water, the mixture being heated under reflux then filtered and the aqueous solution extracted with ether to yield the product.