KR970008311B1 - Preparation process of 3-pyrroline - Google Patents

Abstract

Sys-1,4-dichloro-2-butane is reacted with hexamethylene tetramine to yield chlorinated compound of structural formula(III), then treated with acid in the presence of alcohol to synthesize allyl amine derivative of general formula(IV), and above-mentioned allyl amine derivative and 1,8-diazabicyclo[5,4,0 udecin as base are reacted by closed reflux to yield 3-pyroline without residue; pyrolidine.

Description

Method for preparing 3-pyrroline

The present invention relates to a new method for preparing 3-pyrroline represented by the following structural formula (I).

The compound of formula (I) is a basic raw material widely used to manufacture new agricultural and pharmaceutical products. The commercially available compound is low in purity and contains a large amount of pyrrolidine, a saturated compound of formula (I), as an impurity. Doing. Since high purity is very expensive, it is desired to make this compound cheap and high purity.

In the conventional manufacturing method, since a large amount of impurity pyrrolidine is contained, it is purified by column chromatography or fractional distillation to separate the target compound. There is considerable difficulty in that purification.

However, the present invention does not contain pyrrolidine as an impurity, and in the last step, a new production method can be easily prepared by simply distilling the target compound.

Step by step express the manufacturing method of the present invention.

According to this method, the target compound of formula (I) can be purely produced in high yield without any difficulty of reaction using cheap raw materials as starting materials.

The present invention will be described in detail as follows.

By reacting cis-1,4-dichloro-2-butene with 1 equivalent of hexamethylenetetramine, the compound of formula (III) substituted with chlorine can be prepared in high yield. When the compound is reacted with an acid such as hydrochloric acid in the presence of an alcohol such as ethanol, hexamethylene tarramine is decomposed in a short time to obtain an allylamine derivative as in general formula (IV). After dissolving this compound in the alcohol, the ammonium chloride is filtered off to obtain a pure compound of formula (IV).

The compound (IV) thus obtained is refluxed in the presence of a base such as DBU (1,8-diazabicyclo [5,40] undecine) to obtain the target compound of formula (I), which is directly distilled to give a general formula ( This is the target compound of I), which can be obtained purely in high yield.

As described above, the present invention has a big advantage that the target compound of the general formula (I) can be purely produced in high yield without any separate separation and purification process.

The present invention is explained in detail in the following examples.

Example 1

Preparation of 1-[(Z) -4-chloro-2-butenyl] -1-azo-3,5,7-triazatricyclo [3,3,1,1] decane chloride (III)

After dissolving 34.4 g of hexamethylene tarramine in 500 ml of chloroform, 30.2 g of cis-1,4-dichloro-2-butene was added thereto, and the mixture was refluxed for 4 hours. The reaction was cooled, filtered and washed twice with 50 ml of chloroform. The obtained solid was dried in vacuo to give 58.6 g of the target compound.

Yield: 91%, mp: 160-170 ° C (dec.)

NMR (D ₂ O): 3.54 (d, 2H), 4.10 (d, 2H), 4.4 (d, 2H), 4.58 (d, 3H), 5.0 (d, 6H), 5.7 (m, 1H), 6.2 (m, 1H)

Example 2

Preparation of [(Z) -4-chloro-2-butenyl] ammonium chloride (IV)

To 400 ml of ethanol and 70 ml of concentrated hydrochloric acid solution was added 58.6 g of the compound of formula (III) prepared in Example 1 and stirred. Precipitation formed as it turned to a homogeneous solution. The reaction mixture was stirred overnight at room temperature, cooled to 0 ° C. and ammonium chloride was filtered off. The filtrate was dissolved in 40 ml of ethanol and filtered once more to completely remove residual ammonium chloride. The filtrate was concentrated, 80 ml of ethyl acetate was added to dissolve, and cooled to form a solid. 30 ml of hexane was added thereto, and the crystals were filtered and washed with 60 ml of hexane. The crystal thus produced was vacuum dried to obtain 30 g of the target compound.

Yield: 97%, mp: 117-119 ° C

NMR (D ₂ O): 3.63 (d, 2H), 4.07 (d, 2H), 5.58 (m, 1H), 5.89 (m, 1H)

Example 3

Preparation of 3-Pyrroline (I)

To 66.4 g of 1,8-diazabicyclo [5,4,0] undecine, 30 g of Compound (IV) prepared above was added and refluxed for about 25 minutes. The reaction mixture was distilled at 80-85 ° C. and heating continued until no further compound emerged. Colorless oil obtained the target compound of formula (I).

Yield: 9.5 g (63%)

NMR (CDCl ₃ ): 1.93 (br, NH), 3.74 (s, 4H), 5.84 (br, s, 2H)

Claims (2)

After reacting cis-1,4-dichloro-2-butene of formula (II) with hexamethylenetetramine to prepare a compound of formula (III) and treating it with an acid to prepare an allylamine derivative of formula (IV) Process for preparing 3-pyrroline of formula (I) by ring closure using a base A process for preparing 3-pyrroline of formula (I) according to claim 1, wherein 1,8-diazabicyclo [5,4,0] undecine is used as the base.