PROCESS FOR PREPARING DIHYDROISOXAZOLE DERIVATIVES

Abstract

The present invention relates to a novel process for preparing dihydroisoxazole derivatives.

Claims

1. A process for preparing a compound of formula (I), ##STR00012## in which R.sup.1 is ketone ##STR00013## R.sup.2 is phenyl which is substituted once or more often independently of one another by halogen or C.sub.1-C.sub.4-alkylsulfonyloxy; and R.sup.3 is selected from the group consisting of chlorine and bromine; comprising reacting a compound of formula (II), ##STR00014## in which R.sup.3 is as defined above; via an elimination reaction to form a compound of formula (III) ##STR00015## and reacting the compound of formula (III) which are in situ with a compound of formula (IV) ##STR00016## in which R.sup.2 is as defined above in the presence of a base, an acid and a solvent in acidic pH to form the compound of formula (I).

2. The process according to claim 1, characterized in that R.sup.1 is ketone ##STR00017## R.sup.2 is phenyl substituted with chlorine and methylsulfonyloxy; and R.sup.3 is chlorine.

3. The process according to claim 1 in which the pH is 3.5 to 4.5.

4. The process according to claim 1 in which a buffered solution comprising acetic acid and sodium acetate is used.

5. Use of the compounds of formula (I) according to claim 1 for the preparation of fungicides.

Description

EXAMPLES

Preparation of 3-chloro-2-vinylphenyl methanesulfonate

[0041] ##STR00010##

[0042] 6 g (0.038 mol) of 3-chloro-2-vinylphenol, dissolved in 50 ml toluene, is cooled to 0-5° C. 4.4 g (0.043 mol) triethylamine is added and then a solution of 4.9 g (0.043mo1) methanesulfonic acid chloride in 5 ml toluene is added at 0-5° C. in 15 minutes. After stirring for 1 hour the reaction mixture is poured on ice. Phases are separated and the aqueous phase is extracted with 25 ml toluene. The combined organic phases are washed with 25 ml of water. The solvent is distilled of at 30° C. under vacuum and the residue is cristallised from heptane/tert.butylmethylether.

[0043] 5 g of 3-chloro-2-vinylphenyl methanesulfonate with a purity of 95% is received (yield: 56%).

Preparation of 3-chloro-2-[3-(chloroacetyl)-4,5-dihydro-1,2-oxazol-5-yl]phenyl methanesulfonate

[0044] ##STR00011##

[0045] A mixture of 92 g (0.55 mol) ethyl-4-chloro acetoacetate and 542 g 37% hydrochloric acid is stirred at 25° C. for 24 hours. The mixture is concentrated to 320 g at 40° C. under vacuum and cooled to 5° C. 215 g of 20% sodium hydroxide is added, so that the internal temperature did not exceed 10° C. The mixture is cooled to 0° C. and 159 g of a 20% solution of sodium nitrite is added during 15 minutes. Gas evolution is observed and finally)-1-chloro-3-(hydroxyimino)acetone precipitates. After 30 minutes stirring at 0° C., the mixture is extracted once with 360 ml ethyl acetate and twice with 120 ml ethyl acetate each. To the combined organic phases is added 51 g sodium hydrogencarbonate and 29 g water. 37.6 g of chlorine gas is introduced during 30 min at a temperature of 0-5° C. After stirring for 30 min at 0-5° C. half of the mixture is separated and to this is added 46.4 g of 3-chloro-2-vinylphenyl methanesulfonate (0.199 mol). The mixture is warmed to 35° C. and stirred, while the pH of the mixture is adjusted between 4.3 to 4.5 by addition of a 25% aqueous solution of potassium hydrogencarbonate. The second half of the chloro oxime solution is added after 1 hour. Stirring at 35° C. is continued for further 4 hours, while the pH is kept between 4.3 and 4.5 with a total amount of 129 g 25% potassium hydrogencarbonate. The mixture is cooled to 20° C. and the phases are separated. The organic phase is concentrated to 106 g at 30° C. under vacuum. 160 ml of ethanol is added to the residual oil and the mixture is heated to 70° C. then the mixture is slowly cooled to 20° C. with intermediate seeding. The product precipiates and stirring is continued at 0° C. for 1 hour. The product is filtered off, washed with cold ethanol and dried at 30° C. in vacuum.

[0046] 55.6 g of 3-chloro-2[3-(chloroacetyl)-4,5-dihydro-1,2-oxazol-5-yl]phenyl methanesulfonate with 97% purity were received (yield: 77%).