CS264542B1 - 2- (4'-Acylbiphenyl-4-yl) -5-phenyl-1,3,4-oxadiazoles and a process for the preparation thereof - Google Patents

Abstract

2-(4'-acylbiphenyl-4-yl)-5-phenyl-1,3,4-oxadiazole of the general formula I, where R denotes an alkyl group with 1 to 2 carbon atoms or phenyl or methyl substituted by halogen or benzoylamino group, are derivatives of the industrially produced luminophore 2-biphenylyl-5-phenyl-1,3,4-oxadiazole and serve as intermediates for the synthesis of more complex oxadiazole derivatives, having optical brightening effects. The method of their production consists in treating 2-biphenylyl-5-phenyl-1,3,4-oxadiazole of the formula II with an acyl halide of the general formula RCOX, where R has the meaning given above and X denotes halogen, in the presence of a catalyst of the general formula AlXJf where X is halogen, in an organic anhydrous solvent, at a temperature of 20 to 100 °C.

Description

The invention relates to 2- (4'-acylbiphenyl-4-aB-5-phenyl-1,3,4-oxadiazoles of the general formula I) wherein R represents an alkyl group having 1 to 2 carbon atoms or phenyl or methyl substituted by halogen or benzoylamino These compounds are derivatives of the industrially produced luminophore of 2-biphenylyl-5-phenyl-1,3,4-oxadiazole The new derivatives serve as intermediates for the synthesis of more complex oxadiazole derivatives.

A process for the preparation of 2- (4'-acyl-biphenyl-4-yl) -5-phenyl-1,3,4-oxadiazoles of the general formula I wherein R represents an alkyl group having a carbon number of 1 to 2 or phenyl or methyl substituted by halogen or benzylamino by treating 2-biphenylyl-5-phenyl-1,3,4-oxadiazole of formula II with an acyl halide of formula RCOX, wherein R is as defined above and X is halogen in the presence of a catalyst of formula A1X ₃ , wherein X is halogen, in an organic anhydrous solvent at a temperature of 20 to 100 ° C.

The process is advantageously carried out by treating the 2-biphenylyl-5-phenyl-1,3,4-oxadiazole with a reaction mixture of an acyl halide and a catalyst. Suitable solvents are anhydrous organic solvents. The yield depends on keeping the order of reaction components added, the appropriate solvent and the reaction temperature.

The following examples illustrate the preparation of the compounds of formula (I).

Example 1

134 g A1C1 ₃ was blended with 78.5 g of acetyl chloride and the resulting foaming mass was poured 100 ml of methylene chloride. A solution of 50 g of 2-biphenylyl-5-phenyl-1,3,4-oxadiazole in 500 ml of methylene chloride was then added dropwise to the suspension over 2 hours at low reflux of the reaction mixture. The mixture was then heated with stirring for 8 hours. After completion of the reaction, the mixture was cooled and quenched with water. The organic layer was separated, washed with water to pH = 7 and dried with MgSO ₄ . After evaporation on a evaporator, the solid was recrystallized from acetone-dioxane (1: 1) to give 48.12 g of white crystalline 2- (4'-acetylbiphenyl-4-yl) -5-phenyl-1,3,4- oxadiazole, mp 183.5-184.5 ° C (84%) (I, R = -CH 3)

Example 2

To a mixture of 3.91 g of AlCl ₃ and 5.93 g of bromoacetyl bromide in 25 ml of dichloromethane was added dropwise a solution of 2 g of 2-biphenylyl-5-phenyl-1,3,4-oxadiazole in 35 ml of dichloromethane dropwise at low reflux.

1.5 hours. The mixture was then heated for yet another

2.5 hours and then quenched with 100 ml of water and the precipitate was filtered off with suction. The remaining mother liquors were diluted with 200 mL of dichloromethane and the organic layer was separated, dried over MgSO ₄ and evaporated. The solids were combined and recrystallized from chloroform-acetone. 1.9 g of white acicular crystals of 2- (4'-bromoacetylbiphenyl-4-yl) -5-phenyl-1,3,4-oxadiazole of m.p. 232 DEG-235 DEG C. were obtained. (68%) (I, R = CH ₂ Br).

Example 3

To a mixture of 13.3 g A1C1 ₃ and 14.14 g of benzoyl chloride in 20 ml of nitrobenzene was added dropwise with stirring 3 g of 2-biphenylyl-5-phenyl-l, 3,4-oxadiazole dissolved in 30 ml of nitrobenzene at a water bath temperature of 90 ° C in 70 min. The mixture was then stirred for an additional 4 hours at a bath temperature of 95-100 ° C. After quenching with water and diluting with 200 mL of dichloromethane, the organic layer was separated, washed with 3 x 200 mL of water to neutral pH and dried with CaCl ₂ . After evaporation, the residual solid was stirred with 50 ml of acetone and filtered. 2.56 g of colorless crystalline 2- (4'-benzoylbiphenyl-4-yl) -5-phenyl-1,3,4-oxadiazole with 1.1 were obtained. 175-179 ° C (63%) (I, R = C ₆ H ₃ ).

Example 4

To a suspension of 10 g of 2-biphenylyl-5-phenyl-1,3,4-oxadiazole and 19.87 g of hippuryl chloride in 500 ml CS ₂ was added 53.6 AlCl _{3 with} stirring at room temperature over 1 hour. The reaction mixture was then heated to reflux for 5.5 hours and then allowed to stand overnight. After quenching the mixture of water and ice, the resulting precipitate was filtered off and crystallized from dimethylformamide. 7.23 g of a yellow crystalline substance with a melting point of 242 DEG-245 DEG C. were obtained. (47%) (I, R = -CH ₂ NH — CO — C ₆ H ₅ )

Claims (4)

SUBJECT OF THE INVENTION 2- (4'-Acylbiphenyl-4-yl) -5-phenyl-1,3,4-oxadiazoles of the general formula I, in which R represents an alkyl group having a carbon number of 1 to 2 or phenyl or methyl substituted by halogen or benzoylamino . 2. A process for the preparation of 2- (4'-acylbiphenyl-4-yl) -5-phenyl-1,3,4-oxadiazoles as defined in claim 1, which comprises: 2-biphenylyl-5-phenyl-1; 3,4-oxadiazole of formula II acts with an acyl halide of formula RCOX, wherein R is as defined above and X is halogen, in the presence of a catalyst of formula A1X ₃ , wherein X is as defined above, in an organic anhydrous solvent at 20 to 100 ° C. 3. The method according to claim 2, characterized in that the reaction mixture the acyl halide of formula RCOX, wherein R and X have the aforementioned meanings, and the catalyst of formula A1X _3, where X is as above defined, acts on 2-biphenyl-5- phenyl-1,3,4-oxadiazole of formula II. 4. The process according to claim 2, wherein the reaction is carried out in anhydrous solvents such as carbon disulfide, dichloromethane, dichloroethane, nitrobenzene or other halogenated or nitro-derivative hydrocarbons.