DD234676A1 - PROCESS FOR PREPARING 2-ACYL-3-TRICHLOROMETHYL-2-AZANORBORN-5-ENENE - Google Patents

Abstract

The invention relates to a process for the preparation of 2-acyl-3-trichloromethyl-2-azanorborn-5-enes 1, wherein the azomethines 3 are not isolated, but are reacted immediately after formation with 4. This eliminates a complex step associated with yield losses. By addition of traces of hydroquinone to the reaction mixture as a stabilizer as well as by anaerobic procedure, side reactions of the azomethines 3 are minimized by radical processes, thereby increasing the yield. The addition of 0.1 mol% of freshly sublimed aluminum chloride with respect to 2 leads to a further increase in yield. The azanorbornene derivatives 1 are of interest as crop protection and pest control agents or as starting materials for their synthesis. In addition, these derivatives are starting materials for pharmacologically interesting compounds.

Description

After trituration with absolute cyclohexane, the reaction product crystallizes out and is recrystallized in absolute cyclohexane.

Yield: 10.4 g (= 40.9% of theory.). Mp 88-90 ⁰ C.

Example 2 Preparation of 2-benzoyl-3-trichloromethyl-2-azanorborn-5-ene

The procedure is as described in Example 1. In this case, 28.7 g (0.1 mol) of N- (1,2,2,2-tetrachloroethyl) benzamide are used.

After evaporation of the filtrate is triturated with absolute hexane and the reaction product thus obtained in acetone / hexane recrystallized.

Yield: 10.3 g (= 32.5% d.Th.) Mp 88-91 ⁰ C.

Mitteis NMR spectroscopy was found to be a mixture of isomers of 2-benzoyl-3-exotrichlormethyl-2-azanorborn-5-ene and 2-benzoyl-3-endo-trichloromethyl-2-azanorbom-5-ene in the ratio 68:32 is acting.

(The yield data are based on the Tetrachlorethylacylamide used.)

CCI ₃ CHCi-NHCOR ^ CCI ₃ Ch = NCOR

2 3

Claims (2)

Invention claim: A process for the preparation of 2-acyl-3-trichloromethyl-2-azanorborn-5-enes 1, wherein R = -alkyl of 1 to 4 carbon atoms - cycloalkyl - CH 3 -nCln for n = 1,2,3 - CH 2 -CβHs - Phenyl, which may also be mono- or polysubstituted by chlorine, bromine, methyl and / or nitro groups, characterized in that 1. The isolation of 3a poses difficulties, as 3a is sensitive to atmospheric moisture (addition of water to the C-N double bond). 1. the azomethines 3 are prepared from the N- (1,2,2,2-tetrachloroethyl) acylamides 2 in ketylated benzene under the action of absolute triethylamine at 30 to 40 ° C within 30 minutes, 2. the azomethine thus produced are reacted for 3 without isolation from the reaction mixture with 4 at 60 to 8O ⁰ C within 4 hours, with 4 added to the reaction mixture of 1, 3. the solvent 0.1 mol% fresh sublimed aluminum chloride bezgl. 2 and traces of hydroquinone as a stabilizer contains and 4. work consistently anaerobically. For this 1 page drawing Field of application of the invention The invention relates to a process for the preparation of 2-acyl-3-trichloromethyl-2-azanorbom-5-eriene, which are of interest as crop protection and pest control agents or as starting materials for their synthesis. In addition, these substances are starting materials for pharmacologically interesting compounds. Characteristic of the known technical solutions The only solution known is the synthesis of 2-acetyl-3-exo-trichloromethyl-2-azanorborn-5-ene 1 a *. RAASCH (J. Org. Chemistry 40 [1975], 161) synthesized this compound by reacting N- (1,2,2,2-tetrachloroethyl) acetamide 2a in benzene solution with triethylamine, isolating the resulting azomethine 3a by vacuum distillation and passing through Diels-Alder reaction with cyclopentadiene 4 in benzene solution within 4 hours at 80 ° C, the compound 1 a and in a yield of pure product of 39.4%. d. Th. Isolated.
* Index a stands for R = CH ₃ This method has the following disadvantages: 2. In the synthesis of 3 a, as well as in its isolation and reaction with 4 occurs strong resinification, which reduces the yield. This phenomenon is due to decomposition or oligomerization reactions of 3a due to radical processes. Object of the invention The object of the present invention is to find a generally applicable more efficient process for the preparation of 2-acyl-3-trichloroethyl-2-azanorborn-5-enes 1, wherein the isolation of the unstable azomethines 3 is omitted and side reactions to a minimum be reduced. This should be avoided yield losses and simplify the synthesis route. Explanation of the essence of the invention This object is achieved according to the invention that, in consistently anaerobic operation, the azomethine 3, produced by the action of absolute triethylamine on N- (1,2,2,2-TetrachlorethyOacylamid 2 at 30 to 40 ° C with 4 within 4 hours at 60 to 80 ° C. In this process, ketylated benzene containing 0.1% by volume of freshly sublimed aluminum chloride, based on 2, as catalyst and traces of hydroquinone as stabilizer, is used as solvent. The isolation of the azomethine is omitted. In anaerobic procedure, the resulting triethylamine hydrochloride is filtered off and the filtrate is evaporated in vacuo. After trituration with a suitable solvent (eg cyclohexane, hexane), the crystalline product is filtered off and optionally purified. The procedure is applicable for R = - alkyl of 1 to 4 carbon atoms - Cycloalkyl - CH ₃ . _n C! _n for n = 1,2,3 - CH2-CeHe - Phenyl, which may also be mono- or polysubstituted by chlorine, bromine, methyl and / or nitro groups. embodiments example 1 Preparation of 2-acetyl-3-exo-trichloromethyl - ^ - azanorborn-B-ene In an anaerobic procedure, 22.5 g (0.1 mol) of N- (1,2,2,2-tetrachloroethyl) acetamide are suspended in 200 ml of ketylated benzene and traces of hydroquinone are added. Within 30 minutes at 30 to 40 ⁰ C 10.1 g (0.1 mol) of absolute triethylamine are added dropwise with stirring. To this reaction mixture are added 13 mg (0.1 mol%) of freshly sublimed aluminum chloride and 13.2 g (0.2 mol) of freshly prepared cyclopentadiene. Then under anaerobic conditions for 4 hours at 60 to 8O ⁰ C stirred.
After cooling, the resulting Triethylaminhydrochiorid is anaerobically filtered off and the filtrate evaporated in vacuo.