KR840001185B1 - Process for preparing 2-(3-aryl-5-isoxazol) benzoyl halide - Google Patents

Abstract

Title compd. (I; X, Y=H, trifluoromethyl; X1=halogen) useful as herbicides, were prepd. by the reaction of II and acid halide or H2O. Thus, 30g 3'-(m-trifluouomethhyl-pheyl)- spiro≮isobenzofuran-1(3H), 5'(4'H)-isoxazol≉-3-one, 150 ml thionyl chloride and 5 drops of H2O were refuluxed for 2 hr to give 1.47g 2-≮3-(trifluoromethylphenyl)-5- isoxazole≉benzoyl chloride.

Description

Method for preparing 2- (3-aryl-5-isoxazole) benzoyl halide

The present invention relates to a process for preparing 2- (3-aryl-5-isoxazole) benzoyl halide of the general formula (I).

Wherein X and Y are each hydrogen, halogen, lower alkyl, lower alkoxy, halo-lower-alkyl, phenoxy, phenyl or cyano and X ¹ is chloro, bromo, fluoro or iodo.

Belgian patent 837,454 describes isooxazolyl benzoate as an effective plant growth regulator. Isoxazol-5-yl benzoate is usually prepared by reacting isooxazolin-5-yl benzoate with N-bromosuccinide imide or dichlorodicyano benzoquinone, but isooxazolin-5-yl as starting material Benzoates are prepared from vinyl benzoates that are difficult to prepare.

By the method of the present invention, 3 '-(aryl) -spiro [isobenzofuran-1 (3H), 5' (4'H) -isoxazol] -3-one is reacted with an acid halide in the presence of water Prepare 2- (3-aryl-5-isoxazole) benzoyl halide, wherein 3 '-(aryl) -spiro [isobenzofuran-1 (3H), 5' (4'H) used as starting material here ) -Isoxazol] -3-one is prepared by reacting nitrile oxide with 3-methylenephthalide, as shown in the following scheme:

The “aryl” radicals in this reaction rarely participate in the reaction and can therefore be all aromatic radicals or heteroaromatic radicals (eg pyridyl). However, "aryl" is a radical having the following general formula.

In the above formulae, X and Y are each hydrogen, halogen, lower alkyl, lower alkoxy, halo-lower-alkyl, phenoxy, phenyl or cyano group.

As used herein, the terms “lower alkyl” and “lower alkoxy” refer to straight and branched chain alkyl and alkoxy groups containing up to 5 carbon atoms.

As used herein, the term "halo-lower-alkyl" refers to a lower alkyl group in which one or more or sometimes all of the hydrogens are replaced with halogen atoms.

An example of this halo-lower alkyl group is trifluoromethyl.

As used herein, the term "halogen" refers to chlorine, bromine, fluorine and iodine.

2- (3-aryl-5-isoxazole) benzoyl halide as a compound of the present invention is 3 '(aryl) -spiro [isobenzofuran-1 (3H), 5' (4'H) -isoxazole]- Prepared by reacting 3-one with acid halide in water. In more detail, the benzoyl halide is prepared according to the following scheme:

In the above formula, X ¹ is chloro, bromo, fluoro or iodo and “aryl” is as defined above.

Acid halides, especially acid chlorides, are well known in the art, for example thionyl chloride, thionyl bromide, thionyl fluoride, phosphorus trichloride, phosphorus tribromide, oxalyl chloride, triphenyl phosphine-carbon tetrachloride, PCl ₅ , POBr ₃ and the like. Specifically, reactive halide means a compound containing halide ions that react with carboxylic acid to form acid halides.

In order to prepare benzoyl halides, it is preferred to heat the spiro compound with the acid halide under reflux. The reaction can be carried out even at low temperatures at room temperature, but the reaction rate will be reduced. The reaction may be carried out under high pressure, but the reaction proceeds easily even under atmospheric pressure.

It should be noted that traces of water are required to cause the reaction in this process. If there is no water at all, no benzoyl halide can be produced. Therefore, a small amount of water must be added to the reaction mixture. However, only moisture in the atmosphere can allow the reaction to proceed sufficiently. The important thing is that you have to supply a small amount of moisture anywhere.

In the following Examples the contents of the present invention are described in more detail. These examples are intended to illustrate the invention in more detail, and are not intended to limit the scope of the invention.

Example 1

Preparation of [2- [3- (trifluoromethylphenyl) -5-isoxazole] benzoyl chloride

30 g (0.9 mol) of 3 '-(m-trifluoromethyl-phenyl) spiro [isobenzofuran-1 (3H), 5' (4'H) -isoxazol] -3-one (melting point 170 ° C) ), A solution of 150 ml of thionyl chloride and 5 drops of water was refluxed for 2 hours, cooled and concentrated in vacuo to give 32.7 g of a yellow solid having a melting point of 86 to 89 占 폚. 10 g of this yellow solid is recrystallized from 50 ml of carbon tetrachloride to give 7.1 g of a pale yellow solid having a melting point of 90.5 to 92 ° C. 2.1 g of this pale yellow solid was recrystallized again with carbon tetrachloride to give 1.47 g of pure product as white crystals having a melting point of 91 캜.

Assay for C ₁₇ H ₉ F ₃ ClNO ₂ :

Calculated value; C, 58.05 H, 2.58

Found value; C, 51.67 H, 2.57

Example 2

[Preparation of isopropyl, 2- [3- (3-trifluoro-methylphenyl) isoxazol-5-yl] benzoic acid ester]

The benzoyl chloride of Example 1 is esterified as follows: 5 g (0.0162 water) of 2- [3- [3- (trifluoromethyl) phenyl] -5-isoxazole] benzoyl chloride in 15 ml of pyridine 17 g (0.202 moles) of isopropanol are added and stirred and added in small portions over 10 minutes to the ice-cooled solution. The reaction mixture is left at room temperature for 1 hour, then added to 300 ml of ether, followed by 3 times washing with 1N hydrochloric acid and once with sodium carbonate and finally with water. This ether solution is dried and concentrated to yield 4.94 g of isopropyl ester as a yellow oil. This oil is chromatographed on silica gel column with 50% ethyl acetate, 50% hexane as eluent to afford 3.7 g of pure isopropyl ester. n _D ²⁵ = 1.5426

Analysis of C ₂₀ H ₁₆ F ₃ NO ₃ :

Calculated value; C, 64.00 H, 4.30

Found value; C, 63.99 H, 4.31

The above examples describe effective methods of preparing 3-aryl-isoxazol-5-yl benzoyl halides useful as herbicides and plant growth regulators.

Also, various changes and modifications are possible within the spirit and scope of the present invention.

Claims (1)

3 '-(aryl) spiro [isobenzofuran-1 (3H), 5' (4'H) -isoxazol] -3-one of formula (II) is reacted with an acid halide and water The method of manufacturing the 2- (3-aryl- 5-isoxazole) benzoyl halide of following General formula (I).

In the above formula, X and X are hydrogen or trifluoromethyl, and X ¹ is halogen.