DE1932022C3 - Process for the preparation of 1,2 dihydroquinolines - Google Patents

Description

NH,

converts, in which R is an alkyl radical having 1 to 5 carbon atoms.

2. The method according to claim 1, characterized in the presence of a Lewis acid as a catalyst and

draws that as isopropenyl alkyl ether isoprop- ₄₅ an inert solvent at a temperature

enylethyl ether is used. between room temperature and 52 ° C with 3 to

4 moles of an isopropenyl alkyl ether of the general formula

The invention relates to a process for the preparation of 1,2-dihydroquinolines in general formula

CH, = C - OR

(III)

(I)

wherein the radicals R _{1 are} alkyl radicals having 1 to 5 carbon atoms, R _{2 is} a hydrogen atom and R _{3 is} a straight-chain or branched alkyl radical, or an aryl, acyl, alkoxy, aryloxy, acylamino, nitro, hydroxy or acyloxy group Halogen atom or R ₂ and R ₃ together with the carbon atoms to which they are attached represent a fused-on benzene ring.

converts, wherein R is an alkyl radical having 1 to 5 carbon atoms means.

Compared to the known method mentioned above, the method according to the invention has the Advantage that it can be carried out in a shorter time under much milder process conditions and the catalysts are easily removed from or neutralized in the reaction product can be. Nevertheless, the process according to the invention leads to the same yields as the known one Process (60 to 65%) or in certain cases to even higher yields.

According to the invention, isopropenyl ethyl ether is advantageously used as the isopropenyl alkyl ether.

In the reaction, the catalyst is preferably used in an amount of 1 to 10 percent by weight,

i 932

• based on the weight of the aromatic amine, ! lie.

Ms Lewis acids are boron fluoride advantageous ■; ierat IBF ■ ₃ 0 (C ₂ H,),) or aluminum V ¹ Br _3). As a solvent for the implementation

•, ng suitably serve benzene. Ethyl acetate or 'iioroform.

After the reaction subsided, the 2 to 3 hours. iert, the reaction mixture is iüer with 10% Washed iron liquor, poured over magnesium sulfate and the end product is isolated by vacuum distillation.

During the reaction, which takes place with the release of heat ■ ■ r runs, initially the .ninsan the double formation of the unsaturated Ät'.e .-. s .lier formation of an unstable intermediate. , ic splitting off of alcohol leads to the formation of the Jiiff's base of a ketone. The Schiff base · ■. ■■> Ketone reacts with the second molecule of the unsaturated ether according to the scheme of diene .nthese resulting from the formation of an unstable 4-alkoxy-I 2,3,4-tetrahydroquinoline, which under the reaction conditions alcohol to form the 1,2-dihydro , splits off hinoline derivative.

NH,

N = C

R ₁ OR

CH ₂ = COR

Ri

- RAW

The invention is illustrated in more detail by the following examples.

example 1

6-ethoxy-2,2,4-trimethyl 1-1,2-dihydroquinoline

13.7 g (0.1 mol) of p-phenetidine are dissolved in 50 ml of benzene and 2 g of boron fluoride etherate (BF ₃ · O (C ₂ H ₅ ) ₂ ) are added to the resulting solution. 25.8 g (0.3 mol) of isopropenyl ethyl ether are then felt with stirring. The temperature of the reaction mixture rises to 52 "C. as a result of the exothermic reaction. The mixture is stirred for about 1 hour, then washed with 10% sodium hydroxide solution and dried over magnesium sulfate. Fractionation of the reaction products gives 14 g (64.5%) 6 - ethoxy - 2.2,4 - trimethyl - 1,2 - dihydroquinoline; b.p. 118 to 123 C at 1 Torr, nf 1.5592.

Found ... C 77.43, H 8.89, 8.86%;
calcd ... C 77.38, H 8.98% for C ₁₄ H ₁₉ NO.

Example 2
6-methoxy-2,2,4-trimethyl-1,2-dihydroquinoline

12.3 g (0.1 mol) of p-anisidine are dissolved in 25 ml of benzene J ₅ and 1 ml of boron fluoride etherate (BF ₃ · O (C ₂ H _S ) ₂ ) and then 25.8 g are added to the resulting solution (0.3 mol) of isopropenyl ethyl ether was added. The mixture is cooled somewhat with water. 2 hours after the addition of the ether, the mixture is treated exactly as indicated in Example 1. When the reaction products are distilled, 11.5 g (56.6%) of o-methoxy ^^ trimethyl-U-dihydroquinoline are obtained; Bp. 110 to 113 ° C at 1.5 Torr, K ¹ S 1.5658.

Found ... C 76.71, 77.10, H 8.81, 8.56%;
calcd ... C 76.71, H 8.43% for C ₁₃ H ₁₇ NO.

Example ^: el 3
2,2,4-trimethyl-5,6-benzo-1,2-dihydroquinoline

75 g (0.5 mol) of i-naphthylamine are dissolved in 500 ml of ethyl acetate, and 5 ml of boron fluoride etherate (BF ₃ · 0 (C ₂ H _{5 I 2} ) are added to the resulting solution 170 g (2 mol) of isopropenyl ethyl ether are added dropwise to the mixture at ^{0 ° C. The reaction begins immediately and develops with evolution of heat}

CH ₃ exceeds. Then the mixture is 30 minutes

stirred, then washed with 10% sodium hydroxide solution and dried over magnesium sulfate. During the distillation 103 g (92%) of product are obtained. Bp 134-136 ° C at 1.5 torr "1.6730.

Found ... C 85.42, 85.52, H 7.99, 8.00%;
calcd ... C 86.05, H 7.67% for C ₁₆ H ₁₇ NO.

Example 4
6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline

27.4 g (0.2 mol) of p-phenetidine are dissolved in 100 ml of chloroform, and 3 g of aluminum bromide (AlBr ₃ ) and then 68.8 g (0.8 mol) of isopropenyl ethyl ether are added to the resulting solution. The mixture obtained is treated as indicated in Example 1.

65 The yield of hydroquinoline is 26.9 g (62%).

Claims (1)

Patent claims: 1. Process for the production of 1,2-Dihydrotiiinoliiien the general formula R ₂ R ₁ CH ₃ (D wherein the radicals R _{1 are} alkyl radicals with 1 bir. 5 carbon atoms. R _{2 is} a hydrogen atom and R is a straight-chain or branched alkyl radical. an aryl. Acyl-. Alkoxy, aryloxy, acylamino, nitro, hydroxy or acyloxy group or a halogen atom or R ₂ and R ₃ together with the carbon atoms to which they are bonded denote a benzene ring condensed, characterized in that one Moles of an amine of the general formula (H) NH, in the presence of a Lewis acid as a catalyst and an inert solvent at a temperature between room temperature and 52 ° C. with 3 to 4 mol of an isoprope _n ,, yalkyl ether of the general formula CH, = C - OR (III) These compounds are called antioxidant drugs Stabilizers and herbicides are used. There is already a process for the preparation of substituted 1,2-dihydroquinolines by adding aromatic amines with acetone in the presence of catalysts such as iodine, bromine, benzofluoric acid, toluenesulfonic acid or sulfanilic acid. nut. For example, 6-ethoxy-2,2,4-tnmethyl -! ._ · -Jihydfoquinoline is obtained by adding a slight excess of acetone to 1
! 75 Γ heated p-pheneiidine is passed. As K
lysator is sulfanilic acid in a quantity.,
about 8 percent by weight used (Sammeir
»Synthesis and investigation of effectiveness! stabilizers for polymeric materials «, Voron.shvc-'a - Zeir ilno-Chernosemnoje knishnoje i ..;. ljtelstwo. 19 'p. 180. in Russian). This known method is treated with extraordinary disadvantages. So a high temperature must be used. which leads to side reactions, such as resin formation and demethylation, so that an extraordinary amount of cleaning work is required to separate off the by-products. It is also difficult to separate the catalyst used from the end product. In addition, the acetone consumption is very high high. It is therefore an object of the invention to provide a new one Process for the preparation of the substituted 1,2-dihydroquinolines of the general formula I accessible to make that requires only a small amount of energy and cleaning processes and under much milder conditions can be performed. This object is achieved according to the invention in that one mole of an amine of the general formula R, 40